ci: configure version bump for docs sub-folder

[ricellis]

PR summary

Update bump version config for docs sub-folder.

Fixes: part of s1173

PR Checklist

Please make sure that your PR fulfills the following requirements:

• The commit message follows the
  Angular Commit Message Guidelines.
• Tests for the changes have been added (for bug fixes / features) - build/docs
• Docs have been added / updated (for bug fixes / features) - build/docs

PR Type

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• New tests
• Build/CI related changes
• Documentation content changes
• Other (please describe)

What is the current behavior?

Version bumps update the main README but not the new docs sub-folder.

What is the new behavior?

Docs sub-folder is included in version bumping during release.

Does this PR introduce a breaking change?

• Yes
• No

Other information

Tested locally with a dry-run and it looks correct.