Improve output of vague vale rule

doc/.vale/gitlab/SubstitutionSuggestions.yml

@@ -6,15 +6,15 @@
 #
 # For a list of all options, see https://errata-ai.github.io/vale/styles/
 extends: substitution
-message: 'Consider "%s" instead of "%s".'
+message: 'Consider %s instead of "%s".'
 link: https://docs.gitlab.com/ee/development/documentation/styleguide.html#language
 level: suggestion
 ignorecase: true
 swap:
-  active user: billable user
-  active users: billable users
-  since: because
-  once that: after that
-  once the: after the
-  once you: after you
-  within: in
+  active user: '"billable user"'
+  active users: '"billable users"'
+  since: '"because" or "after"'
+  once that: '"after that"'
+  once the: '"after the"'
+  once you: '"after you"'
+  within: '"in"'