[REF][MOV] documentation apocalypse

Prior to this commit, the Odoo documentation was mainly split between
two repositories: odoo/odoo/doc and odoo/documentation-user. Some bits
of documentation were also hosted elsewhere (e.g., wiki, upgrade, ...).
This was causing several problems among which:
  - The theme, config, Makefile, and similar technical resources had to
    be duplicated. This resulted in inconsistent layout, features, and
    build environments from one documentation to another.
  - Some pages did not fit either documentation as they were relevant
    for both users and developers. Some were relevant to neither of the
    two (e.g., DB management).
  - Cross-doc references had to be absolute links and they broke often.
  - Merging large image files in the developer documentation would bloat
    the odoo/odoo repository. Some contributions had to be lightened to
    avoid merging too many images (e.g., Odoo development tutorials).
  - Long-time contributors to the user documentation were chilly about
    going through the merging process of the developer documentation
    because of the runbot, mergebot, `odoo-dev` repository, etc.
  - Some contributors would look for the developer documentation in the
    `odoo/documentation-user` repository.
  - Community issues about the user documentation were submitted on the
    `odoo/odoo` repository and vice-versa.

Merging all documentations in one repository will allow us to have one
place, one theme, one work process, and one set of tools (build
environment, ...) for all of the Odoo docs.

As this is a good opportunity to revamp the layout of the documentation,
a brand new theme replaces the old one. It features a new way to
navigate the documentation, centered on the idea of always letting the
reader know what is the context (enclosing section, child pages, page
structure ...) of the page they are reading. The previous theme would
quickly confuse readers as they navigated the documentation and followed
cross-application links.

The chance is also taken to get rid of all the technical dangling parts,
performance issues, and left-overs. Except for some page-specific JS
scripts, the Odoo theme Sphinx extension is re-written from scratch
based on the latest Sphinx release to benefit from the improvements and
ease future contributions.

task-2351938
task-2352371
task-2205684
task-2352544

Closes #945

content/applications/finance/accounting/receivables/customer_payments/check.rst

@@ -0,0 +1,151 @@
+============================================
+How to register customer payments by checks?
+============================================
+
+There are two ways to handle payments received by checks. Odoo support
+both approaches so that you can use the one that better fits your
+habits.
+
+1. **Undeposited Funds:** 
+   once you receive the check, you record a payment
+   by check on the invoice. (using a Check journal and posted on the
+   Undeposited Fund account) Then, once the check arrives in your
+   bank account, move money from Undeposited Funds to your bank
+   account.
+
+2. **One journal entry only:** 
+   once your receive the check, you record a
+   payment on your bank, paid by check, without going through the
+   **Undeposited Funds**. Once you process your bank statement, you do
+   the matching with your bank feed and the check payment, without
+   creating a dedicated journal entry.
+
+We recommend the first approach as it is more accurate (your bank
+account balance is accurate, taking into accounts checks that have not
+been cashed yet). Both approaches require the same effort.
+
+Even if the first method is cleaner, Odoo support the second approach
+because some accountants are used to it (quickbooks and peachtree
+users).
+
+.. Note:: 
+  You may have a look at the *Deposit Ticket feature* if you deposit
+  several checks to your bank accounts in batch.
+
+Option 1: Undeposited Funds
+===========================
+
+Configuration
+-------------
+
+-  Create a journal **Checks**
+
+-  Set **Undeposited Checks** as a defaut credit/debit account
+
+-  Set the bank account related to this journal as **Allow Reconciliation**
+
+From check payments to bank statements
+--------------------------------------
+
+The first way to handle checks is to create a check journal. Thus,
+checks become a payment method in itself and you will record two
+transactions.
+
+Once you receive a customer check, go to the related invoice and click
+on **Register Payment**. Fill in the information about the payment:
+
+-  Payment method: Check Journal (that you configured with the debit and
+   credit default accounts as **Undeposited Funds**)
+
+-  Memo: write the Check number
+
+.. image:: ./media/check02.png
+  :align: center
+
+This operation will produce the following journal entry:
+
++----------------------+-------------------+----------+----------+
+| Account              | Statement Match   | Debit    | Credit   |
++======================+===================+==========+==========+
+| Account Receivable   |                   |          | 100.00   |
++----------------------+-------------------+----------+----------+
+| Undeposited Funds    |                   | 100.00   |          |
++----------------------+-------------------+----------+----------+
+
+The invoice is marked as paid as soon as you record the check.
+
+Then, once you get the bank statements, you will match this statement
+with the check that is in Undeposited Funds.
+
++---------------------+-------------------+----------+----------+
+| Account             | Statement Match   | Debit    | Credit   |
++=====================+===================+==========+==========+
+| Undeposited Funds   | X                 |          | 100.00   |
++---------------------+-------------------+----------+----------+
+| Bank                |                   | 100.00   |          |
++---------------------+-------------------+----------+----------+
+
+
+If you use this approach to manage received checks, you get the list of
+checks that have not been cashed in the **Undeposit Funds** account
+(accessible, for example, from the general ledger).
+
+.. Note:: 
+    Both methods will produce the same data in your accounting at the
+    end of the process. But, if you have checks that have not been cashed,
+    this one is cleaner because those checks have not been reported yet on
+    your bank account.
+
+Option 2: One journal entry only
+================================
+
+Configuration
+-------------
+
+These is nothing to configure if you plan to manage your checks using
+this method.
+
+From check payments to bank statements
+--------------------------------------
+
+Once you receive a customer check, go to the related invoice and click
+on **Register Payment**. Fill in the information about the payment:
+
+-  **Payment method:** the bank that will be used for the deposit
+
+-  Memo: write the check number
+
+.. image:: ./media/check03.png
+  :align: center
+
+The invoice is marked as paid as soon as you record the check.
+
+Once you will receive the bank statements, you will do the matching with
+the statement and this actual payment. (technically: point this payment
+and relate it to the statement line)
+
+With this approach, you will get the following journal entry in your
+books:
+
++----------------------+-------------------+----------+----------+
+| Account              | Statement Match   | Debit    | Credit   |
++======================+===================+==========+==========+
+| Account Receivable   | X                 |          | 100.00   |
++----------------------+-------------------+----------+----------+
+| Bank                 |                   | 100.00   |          |
++----------------------+-------------------+----------+----------+
+
+.. tip:: 
+    You may also record the payment directly without going on the
+    customer invoice, using the menu :menuselection:`Sales --> Payments`. This method may
+    be more convenient if you have a lot of checks to record in a batch but
+    you will have to reconcile entries afterwards (matching payments with
+    invoices)
+
+If you use this approach to manage received checks, you can use the
+report **Bank Reconciliation Report** to verify which checks have been
+received or paid by the bank. (this report is available from the **More**
+option from the Accounting dashboard on the related bank account).
+
+.. image:: ./media/check01.png
+  :align: center