Update label automation to avoid docs linting changes

lib/gitlab/danger/helper.rb

@@ -102,7 +102,7 @@ module Gitlab
       }.freeze
       # First-match win, so be sure to put more specific regex at the top...
       CATEGORIES = {
-        %r{\Adoc/} => :docs,
+        %r{\Adoc/.*(\.(md|png|gif|jpg))\z} => :docs,
         %r{\A(CONTRIBUTING|LICENSE|MAINTENANCE|PHILOSOPHY|PROCESS|README)(\.md)?\z} => :docs,
 
         %r{\A(ee/)?app/(assets|views)/} => :frontend,

spec/lib/gitlab/danger/helper_spec.rb

@@ -167,7 +167,7 @@ RSpec.describe Gitlab::Danger::Helper do
 
   describe '#categories_for_file' do
     where(:path, :expected_categories) do
-      'doc/foo'         | [:docs]
+      'doc/foo.md'      | [:docs]
       'CONTRIBUTING.md' | [:docs]
       'LICENSE'         | [:docs]
       'MAINTENANCE.md'  | [:docs]