message: Add `skip` documentation
  As per
diff: @@ -54,6 +54,8 @@ Make sure to replace the value of `projectToken` with the project token provided
  exitZeroOnChanges: 'Positive exit of action even when there are changes: boolean or branchname'
  exitOnceUploaded: 'Exit with 0 once the built version has been sent to chromatic: boolean or branchname'
  ignoreLastBuildOnBranch: 'Ignores latest build on target branch as a baseline if branch is no longer present in history (i.e. branch was rebased): branchname'
  + skip: 'Skip Chromatic tests, but mark the commit as passing. Avoids blocking PRs due to required merge checks: boolean or branchname.
  +'
  ```
  