Merge changes from topic "pb/sphinx-doc" into integration

* changes:
  doc: Use proper note and warning annotations
  doc: Refactor contributor acknowledgements
  doc: Reorganise images and update links
  doc: Set correct syntax highlighting style
  doc: Add minimal glossary
  doc: Remove per-page contents lists
  doc: Make checkpatch ignore rst files
  doc: Format security advisory titles and headings
  doc: Reformat platform port documents
  doc: Normalise section numbering and headings
  doc: Reword document titles

docs/process/security-center.rst → docs/process/security.rst

-Security Center
-===============
+Security Handling
+=================
 
 Security Disclosures
 --------------------