[IMP] upgrade: overhaul upgrade doc

closes #6316

X-original-commit: 41aebc3
Signed-off-by: Nathan Marotte (nama) <nama@odoo.com>

Author: nmarotte

content/administration/maintain/odoo_online.rst

@@ -30,8 +30,8 @@ Upgrade
 Trigger a database upgrade.
 
 .. seealso::
-   For more information about the upgrade process, check out the :doc:`Odoo Online upgrade
-   documentation <../upgrade/odoo_online>`.
+   For more information about the upgrade process, check out the :ref:`Odoo Online upgrade
+   documentation <upgrade/request-test-database>`.
 
 .. _odoo_online/duplicate:
 

content/administration/odoo_sh/getting_started/branches.rst

@@ -295,7 +295,7 @@ Upgrade
 Available for production and staging branches for valid projects.
 
 .. seealso::
-    :doc:`Upgrade - Odoo.sh <../../upgrade/odoo_sh>`
+    :doc:`Upgrade documentation <../../upgrade>`
 
 .. _odoosh-gettingstarted-branches-tabs-settings: