[MOV] accounting: restructuration of the accounting documentation

This commit improves the structure of the accounting documentation by
- reducing the levels necessary to reach the information
- grouping some docs
- moving content to their parent category page (content in all levels)
- renaming some sections to reflect the structure of the app better

task-3330093

closes odoo/documentation#4477

Signed-off-by: Castillo Jonathan (jcs) <jcs@odoo.com>

content/applications/finance/accounting/bank/foreign_currency.rst

@@ -0,0 +1,117 @@
+===========================================
+Manage a bank account in a foreign currency
+===========================================
+
+In Odoo, every transaction is recorded in the default currency of the company, and reports are all
+based on that default currency. When you have a bank account in a foreign currency, for every
+transaction, Odoo stores two values:
+
+-  The debit/credit in the currency of the *company*;
+-  The debit/credit in the currency of the *bank account*.
+
+Currency rates are updated automatically using the web services of a banking institution. By
+default, Odoo uses the European Central Bank's web services but other options are available.
+
+Configuration
+=============
+
+Activate multi-currencies
+-------------------------
+
+To work with multiple currencies, go to :menuselection:`Accounting --> Configuration --> Settings
+--> Currencies` and tick :guilabel:`Multi-Currencies`. Under :guilabel:`Post Exchange difference
+entries in:`, provide a :guilabel:`Journal`, a :guilabel:`Gain Account`, a :guilabel:`Loss Account`,
+and then click on :guilabel:`Save`.
+
+Configure currencies
+--------------------
+
+Once Odoo is configured to support multiple currencies, they are all created by default, but not
+necessarily active. To activate the new currencies, click on :guilabel:`Activate Other Currencies`
+under the :guilabel:`Multi-Currencies` setting or go to :menuselection:`Accounting --> Configuration
+--> Accounting: Currencies`.
+
+When the currencies are activated, you can choose to **automate** the currency rate update, or leave
+it on **manual**. To configure the rate update, go back to :menuselection:`Accounting -->
+Configuration --> Settings --> Currencies`, check :guilabel:`Automatic Currency Rates`, set
+:guilabel:`Interval` to your desired frequency, and then click on :guilabel:`Save`. You also have
+the option to choose the :guilabel:`Service` you wish to obtain currency rates from.
+
+Click on the Update now button (:guilabel:`🗘`) besides the :guilabel:`Next Run` field to update
+the currency rates manually.
+
+Create a new bank account
+-------------------------
+
+In the accounting application, go to :menuselection:`Accounting --> Configuration --> Journals` and
+create a new one. Enter a :guilabel:`Journal Name` and set the :guilabel:`Type` to `Bank`. In the
+:guilabel:`Journal Entries` tab, enter a **short code**, a **currency**, and then finally click on
+the :guilabel:`Bank Account` field to create a new account. In the pop-up window of the account
+creation, enter a name, a code (ex.: 550007), set its type to `Bank and Cash`, set a currency type,
+and save. When you are back on the **journal**, click on the :guilabel:`Account Number` field, and
+in the pop-up window, fill out the :guilabel:`Account Number`, :guilabel:`Bank` of your account, and
+save.
+
+.. image:: foreign_currency/foreign-journal.png
+   :align: center
+   :alt: Example of a created bank journal.
+
+Upon creation of the journal, Odoo automatically links the bank account to the journal. It can be
+found under :menuselection:`Accounting --> Configuration --> Accounting: Chart of Accounts`.
+
+Vendor bill in a foreign currency
+=================================
+
+To pay a bill in a foreign currency, simply select the currency next to the :guilabel:`Journal`
+field and register the payment. Odoo automatically creates and posts the foreign **exchange gain or
+loss** as a new journal entry.
+
+.. image:: foreign_currency/foreign-bill-currency.png
+   :align: center
+   :alt: How to set a bill currency.
+
+.. note::
+   Note that you can pay a foreign bill with another currency. In that case, Odoo automatically
+   converts between the two currencies.
+
+Unrealized Currency Gains/Losses Report
+=======================================
+
+This report gives an overview of all unrealized amounts in a foreign currency on your balance sheet,
+and allows you to adjust an entry or manually set an exchange rate. To access this report, go to
+:menuselection:`Reporting --> Management: Unrealized Currency Gains/Losses`. From here, you have
+access to all open entries in your **balance sheet**.
+
+.. image:: foreign_currency/foreign-gains-losses.png
+   :align: center
+   :alt: View of the Unrealized Gains/Losses journal.
+
+If you wish to use a different currency rate than the one set in :menuselection:`Accounting -->
+Configuration --> Settings --> Currencies`, click the :guilabel:`Exchange Rates` button and change
+the rate of the foreign currencies in the report.
+
+.. image:: foreign_currency/foreign-exchange-rates.png
+   :align: center
+   :alt: Menu to manually change exchange rates.
+
+When manually changing **exchange rates**, a yellow banner appears allowing you to reset back to
+Odoo's rate. To do so, simply click on :guilabel:`Reset to Odoo's Rate`.
+
+.. image:: foreign_currency/foreign-reset-rates.png
+   :align: center
+   :alt: Banner to reset back to Odoo's rates.
+
+In order to update your **balance sheet** with the amount of the :guilabel:`adjustment` column,
+click on the :guilabel:`Adjustment Entry` button. In the pop-up window, select a
+:guilabel:`Journal`, :guilabel:`Expense Account` and :guilabel:`Income Account` to calculate and
+process the **unrealized gains and losses**.
+
+You can set the date of the report in the :guilabel:`Date` field. Odoo automatically reverses the
+booking entry to the date set in :guilabel:`Reversal Date`.
+
+Once posted, the :guilabel:`adjustment` column should indicate `0.00`, meaning all **unrealized
+gains/losses** have been adjusted.
+
+.. image:: foreign_currency/foreign-adjustment.png
+   :align: center
+   :alt: Unrealized Currency Gains/Losses report once adjusted.