[VOL-5252] Update release matrix for repo:voltha-openonu-adapter-go

release_notes/voltha_2.12.rst
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  o Update release matrix with onu-adapter-go artifact and chart version.

howto/release/tasks/charts.rst
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  o Create an anchored document for chart editing.
  o This common document can then be referenced by per-repo chart edit docs.

howto/release/charts/notes.rst
howto/release/charts/voltha-openolt-adapter.rst
howto/release/charts/voltha-openonu-adapter.rst
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  o Document edits for openonu.
  o Re-arrange some of the content.

howto/code/index.rst
howto/code/lint/
howto/code/linting.rst
----------------------
  o Move help topics lint-chart and lint-helm into an individual rst file.
  o This helps support creation of an anchor for document linking.

Change-Id: I03bf4742a3ce8075c93827004466f9c1d7408859
11 files changed