Misc doc edits for release.

release_notes/voltha_2.12.rst
-----------------------------
  o Update version and URLs for kafka
  o Update version and URLs for olt

howto/release/tasks/index.rst
howto/release/tasks/golang_gofmt_syntax.rst
-------------------------------------------
  o Document std golang formatting with gofmt -s -e -w.
  o Document content with references (commit message, make lint)
    diff --git a/howto/release/tasks/index.rst b/

Include a few edits from gerrit id I6e9658c23f436f83d423f74e01b2966943d2fe08

Change-Id: I27ad46ddd6673a9e35e794b1d3e8bb0644e8260d
diff --git a/howto/release/tasks/go_mod_update.rst b/howto/release/tasks/go_mod_update.rst
new file mode 100644
index 0000000..171046f
--- /dev/null
+++ b/howto/release/tasks/go_mod_update.rst
@@ -0,0 +1,52 @@
+.. _Release Task Golang Mod Update:
+
+GOLANG: Update go.mod opencord package versions
+===============================================
+
+Update go package version dependencies.
+
+NOTE: Files in the vendor/ directory should not be modified
+
+- Sources are checked in purely for bootstrapping.
+- Ideally vendor/ will be deleted and populated dynamically by git submodules.
+
+.. code-block:: shell-session
+   :caption: Update copyrigth notice ending date.
+
+   % git clone ssh://gerrit.opencord.org:29418/ofagent-go.git
+   % cd ofagent-go
+
+   # ---------------------------------------
+   # Preview packages and versions to modify
+   # ---------------------------------------
+   % grep opencord $(find . ! -path 'vendor/*' -name '*.go' -print)
+
+   # --------------------------------------------------------------
+   # Edit go.mod and update dependencies as needed
+   # --------------------------------------------------------------
+   % ${EDITOR} $(find . ! -path 'vendor/*' -name '*.go' -print)
+
+   % make distclean
+
+   # ------------------------------
+   # Bulk fix golang linting errors
+   # ------------------------------
+   % find . ! -path 'vendor/*' -name '*.go' -print0 | xargs -0 gofmt -s -e -w
+
+   # ---------------------------
+   # Invoke go mod vendor
+   # Invoke go mod tidy
+   # From within a local sandbox
+   # ---------------------------
+   % make mod-update LOCAL_FIX_PERMS=1
+
+   # -------------------------
+   # Check for syntax problems
+   # -------------------------
+   % make lint
+
+   # -----------------------------------
+   # Pre-screen for jenkins job problems
+   # -----------------------------------
+   % make build
+   % make test