ci: widen regex for skipping ci on docs branches

.gitlab-ci.yml

@@ -8,7 +8,7 @@ workflow:
     # run pipeline on commits to default branch
     - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
     # skip pipeline for branches that start with "docs"
-    - if: '$CI_COMMIT_REF_NAME =~ /^docs/'
+    - if: '$CI_COMMIT_REF_NAME =~ /^doc*/i'
       when: never
 
 # include templates