[ADD] email_communication: new documentation regarding general emailing

Creation of a new submenu under Applications/General for the Email communication.
Moved advanced of dicuss to this new submenu + adding of content regarding
frequently asked question in support.

Redirection has been done on other files pointing to Discuss/Advanced to match
the new folder email_communication.

Modified content in:
- Email servers: split and move configuration part under email_domain
- Email domain: covering information about SPF DKIM and DMARC configurations by JQU
- Email templates: (how to use the functions) by GOR
- Email common: answering frequently asked questions + common issues by ALA

closes odoo/documentation#1525

X-original-commit: cf6af904f9
Signed-off-by: Vergote Baptiste (bve) <bve@odoo.com>

content/administration/odoo_sh/getting_started/branches.rst

@@ -213,6 +213,8 @@ This link contains various monitoring metrics of the current build.
 You can zoom, change the time range or select a specific metric on each graph.
 On the graphs, annotations help you relate to changes on the build (database import, git push, etc...).
 
+.. _odoosh/logs:
+
 Logs
 ----
 A viewer to have a look to your server logs.
@@ -382,7 +384,9 @@ we are considering the feature if there is enough demand.
 In case the domain of your users email addresses use SPF (Sender Policy Framework) or DKIM
 (DomainKeys Identified Mail), don't forget to authorize Odoo as a sending host in your domain name
 settings to increase the deliverability of your outgoing emails.
-The configuration steps are explained in the :ref:`Discuss app documentation <discuss-email_servers-spf-compliant>`.
+The configuration steps are explained in the documentation about :ref:`SPF 
+<email_communication/spf_compliant>` and :ref:`DKIM <email_communication/dkim_compliant>`.
+
 
 .. Warning::
   Forgetting to configure your SPF or DKIM to authorize Odoo as a sending host can lead to the