[MOV] documentation structure reorganization

This commit aims to improve the documentation's navigability by
redefining some categories' purposes and titles.

There is a redirection rule for each documentation page moved.
This ensures that users won't have a 404 error message.

task-3217827

closes odoo/documentation#8063

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

content/applications/services/helpdesk/overview/getting_started.rst

@@ -169,8 +169,8 @@ customer when a ticket reaches that specific stage in the pipeline. Likewise, ad
 :guilabel:`SMS Template` triggers an SMS text message to send to the customer.
 
 .. important::
-   SMS Text Messaging is an :doc:`In-App Purchase (IAP) <../../../general/in_app_purchase/>` service
-   that requires prepaid credits to work. Refer to `SMS Pricing FAQ
+   SMS Text Messaging is an :doc:`In-App Purchase (IAP) </applications/essentials/in_app_purchase/>`
+   service that requires prepaid credits to work. Refer to `SMS Pricing FAQ
    <https://iap-services.odoo.com/iap/sms/pricing>`_ for additional information.
 
 To select an existing email template, select it from the :guilabel:`Email Template` field. Click on
@@ -186,7 +186,7 @@ Follow the same steps to select, edit, or create an :guilabel:`SMS Template`.
    :alt: View of an SMS template setup page in Odoo Helpdesk
 
 .. seealso::
-   :doc:`../../../general/email_communication/email_template`
+   :doc:`/applications/general/companies/email_template`
 
 Assign stages to a team
 -----------------------