Merge branch '292901-expand-vale-substitutions-list' into 'master'

Docs: expand Vale substitutions list

See merge request gitlab-org/gitlab!49795

doc/.vale/gitlab/SubstitutionSuggestions.yml

@@ -13,8 +13,9 @@ ignorecase: true
 swap:
   active user: '"billable user"'
   active users: '"billable users"'
-  since: '"because" or "after"'
+  docs: documentation
   once that: '"after that"'
   once the: '"after the"'
   once you: '"after you"'
+  since: '"because" or "after"'
   within: '"in"'