Add documentation link

data/release_posts/unreleased/error-tracking-sort-by-frequency.yml

@@ -2,7 +2,7 @@ features:
   secondary:
     - name: 'Sort error list by first seen, last seen and frequency'
       available_in: [core, starter, premium, ultimate]
-      documentation_link: ''
+      documentation_link: 'https://docs.gitlab.com/ee/user/project/operations/error_tracking.html#error-tracking-list'
       image_url: '/images/unreleased/error-sorting.png'
       reporter: swaldner
       stage: monitor