[VOL-5061] - docs.voltha.org: Update release page.On branch dev-joey

[VOL-5079]

conf.py
sphinx_conf/exclude_patterns.py
sphinx_conf/linkcheck_ignore.py
-------------------------------
  o Refactor large URL and path exclusion lists into separate files.
  o Update linkcheck release_notes/*.html patterns to exclude by regex.

release_notes/voltha_2.12.rst
-----------------------------
  o Update deployed package grid with current version strings.
  o Re-arrange structure to display 'artifacts', include links
    for pkg, pkg-app and pkg-api artifact downloads.
  o Replace sonatype/nexus urls(staging) with direct links to maven central.

requirements.txt
----------------
  o Added missing python package sphinx-reload.

howto/release/components/apache-karaf/
howto/release/components/atomix/
howto/release/components/onos/
--------------------------------------
  o Capture dependencies, version upgrades and sources to endit
    for current package release deployments.

To view changes live:
  o git checkout voltha-docs
  o cd voltha-docs
  o make reload

Change-Id: I7b88f9d4d3329abcbe98ebbb4dbb94587088f8b9
10 files changed