Consider :none as docs only change

• Follows up on the discussion here: !20729 (comment 252944658)
• Related issue: #37340 (closed)

What does this MR do?

This disables the changelog check on both :docs and :none change types. We originally wanted to prevent Danger from asking for a changelog when documentation-only changes are pushed and we did that by checking the :docs type: !20729 (diffs)

However, it looks like docs changes aren't marked with the :docs type but rather with the :none type currently:

• https://gitlab.com/gitlab-org/gitlab/blob/c90c0262eae868f5da62413e1b69b2e16eddd402/lib/gitlab/danger/helper.rb#L100-101
• https://gitlab.com/gitlab-org/gitlab/blob/c90c0262eae868f5da62413e1b69b2e16eddd402/lib/gitlab/danger/helper.rb#L156-159

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers

Closes #37340 (closed)