docs.voltha.org::HOWTO edits and WARNING cleanups.

Makefile
--------
  o Added convenience target 'make warnings' to help search for problems.

config.py
---------
  o Add more exclusions for .venv/ so sphinx will stop checking sources.

howto/edit_voltha_docs.rts
howto/docs.voltha.org/index.rst
howto/docs.voltha.org/quickstart.rst
howto/docs.voltha.org/edit_voltha_docs.rst
------------------------------------------
  o Added a quickstart guide for editing repo:voltha-docs

Misc
----
  o Fixed several WARNINGS
  o Add missing documents in index.rst

Change-Id: I0b3d01cc4116d40bd84db49649669253d6135546
diff --git a/howto/release/components/index.rst b/howto/release/components/index.rst
index 02bd2a9..77c45c5 100644
--- a/howto/release/components/index.rst
+++ b/howto/release/components/index.rst
@@ -8,7 +8,8 @@
    onos_dependencies
    voltha-protos
 
-   voltctl/index
-   voltctl/install
-   voltctl/release
-   voltctl/see_also
+   voltha-go.rst
+   voltha-lib-go
+   voltha-onos
+   voltha-openolt-adapter
+   voltha-openonu-adapter-go