[VOL-5009] Update release notes, jira tickets.

release_notes/voltha_2.12.rst
-----------------------------
  o Update Jira/Bug Fixes/Test from Mahir(s) Confluence page attached
    to VOL-5009.
  o Experimenting with rst replace/substitute text directive.  Declare
    server/domain as a replacement string to simplify linuxfoundation.org
    migration tasks later on.
  o Update release version string for components:
      bbsim-sadis-server
      voltha-openolt-adapter
      voltha-openonu-adapter-go

Change-Id: I184498d4d984d7b3751dbbe0db63f985ab6bff39
2 files changed