Added a HOWTO page release based source edits.

conf.py
-------
   * Exclude all variants of python virtual env from traversal.
   * Exclude __pycache__ from document traversal.

index.rst
---------
   * Create a top level index link/page for release howto(s).

overview/contributing.rst
-------------------------
   * Document version based script edits required at time of release.
   * This URL will be used by repo:ci-management/vars/installVoltctl
     to display self-documenting help.

*/urls
------
   * Added placeholders and resources for documenting future topics.

Chaser edits:
-------------
   o Bump VERSION string.
   o 'stern' URL in unrelated troublteshooting.rst doc failed link check:
      + github repo no longer exists.
      + add replacement github/stern/stern

Change-Id: I2f0f15eb5ba7bd6817806296928964df5259b21a
diff --git a/howto/code/urls b/howto/code/urls
new file mode 100644
index 0000000..390f491
--- /dev/null
+++ b/howto/code/urls
@@ -0,0 +1,6 @@
+# placeholder for a future howto topic
+
+# Guidelines, patches, 
+https://docs.voltha.org/master/overview/contributing.html?highlight=commit%20message%20triggers
+
+# EOF
\ No newline at end of file
diff --git a/howto/code/versioning/urls b/howto/code/versioning/urls
new file mode 100644
index 0000000..5c2ac62
--- /dev/null
+++ b/howto/code/versioning/urls
@@ -0,0 +1,13 @@
+
+https://docs.voltha.org/master/overview/contributing.html
+
+Versioning
+
+All of the VOLTHA components and the charts include a VERSION file that specifies the version of the service, library, protobuf, test suite included in the repository. The VERSION is in the format and follows the SemVer principles VOLTHA also follows the guidelines on how to increment versions as described in the SemVer specification.
+
+Each increment of the VERSION file in a patch automatically triggers publishing of the repository artifact, e.g. docker images, with that tag. In VOLTHA we also use a x.y.z-dev format which identifies a non-released component (what is master). When a patch is merged with the -dev suffix in the VERSION file no artifact is published except for master docker images. The -dev suffix should be removed when a feature being worked on and the component is ready for release.
+
+We expect contributions to the VOLTHA codebase to follow these rules when submitting a patch and the same rules to be enforced by reviewers during the core review process.
+
+
+