[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#8064

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

content/developer/tutorials/backend.rst

@@ -11,7 +11,7 @@ Building a Module
    This tutorial is outdated. We recommend reading :doc:`getting_started` instead.
 
 .. warning::
-   This tutorial requires :doc:`having installed Odoo <../../administration/install>`
+   This tutorial requires :doc:`having installed Odoo </administration/on_premise>`
 
 Start/Stop the Odoo server
 ==========================

content/developer/tutorials/web.rst

@@ -24,7 +24,7 @@ or extend existing business systems of Odoo, see :doc:`backend`.
     * jQuery_
     * `Underscore.js`_
 
-    It also requires :doc:`an installed Odoo <../../administration/install>`, and Git_.
+    It also requires :doc:`an installed Odoo </administration/on_premise>`, and Git_.
 
 A Simple Module
 ===============

content/developer/tutorials/website.rst

@@ -11,7 +11,7 @@ Building a Website
 
     * This guide assumes `basic knowledge of Python
       <http://docs.python.org/2/tutorial/>`_
-    * This guide assumes :doc:`an installed Odoo <../../administration/install>`
+    * This guide assumes :doc:`an installed Odoo </administration/on_premise>`
 
 Creating a basic module
 =======================