Update contributions.topic

Author: andrey-helldar

docs/topics/contributions.topic

@@ -176,7 +176,7 @@
  The compliance of the title with the established format is checked by a regular expression:
  </p>
  <code-block lang="bash">
- /^(Draft:\s)?\[([a-z]{2,3}(_[a-zA-Z]+){0,2})\]:\s.+$/g
+ /^(Draft:\\s)?\\[(source|docs|app|[a-z]{2,3}(_[a-zA-Z]+){0,2})\\]:\\s.+$/g
  </code-block>
  </chapter>