Move developer documentation to top level

It's harder to find as part of the install guide, and shouldn't be there
anyway.

Related-Bug: #1804642
Change-Id: Ia677ced783da6383211fb0bb7a28ec5fb2f538fe

doc/source/developer/tht_walkthrough/tls_for_services.rst

@@ -224,7 +224,7 @@ Internal TLS
 How it works
 ~~~~~~~~~~~~
 
-If you haven't read the section :doc:`../../advanced_deployment/tls_everywhere`
+If you haven't read the section :doc:`../../install/advanced_deployment/tls_everywhere`
 it is highly recommended you read that first before continuing.
 
 As mentioned, the default CA is FreeIPA, which issues the certificates that the
@@ -387,7 +387,7 @@ template. This section will be in the same level as ``config_settings`` and
 Note that it merely outputs the metadata_settings section that the apache base
 stack already outputs. This will give the appropriate parameters to a hook that
 sets the nova metadata, which in turn will be taken by the *novajoin* service
-(which was mentioned in the :doc:`../../advanced_deployment/tls_everywhere`
+(which was mentioned in the :doc:`../../install/advanced_deployment/tls_everywhere`
 section) to generate the service principals for httpd for the host.
 
 .. _configuring-haproxy-internal-tls:

doc/source/index.rst

@@ -34,6 +34,14 @@ Upgrades/Updates/FFWD-Upgrade
 
   upgrade/index
 
+Developer Guide
+---------------
+
+.. toctree::
+  :maxdepth: 3
+  :includehidden:
+
+  developer/index
 
 Documentation Conventions
 =========================

doc/source/install/index.rst

@@ -23,4 +23,3 @@ TripleO Install Guide
   troubleshooting/troubleshooting
   validations/validations
   mistral-api/mistral-api
-  developer/developer