Merge branch '211983-docs-aqualls-substitution-warnings' into 'master'

Docs: add Vale test for warning-level substitutions

Closes #211983

See merge request gitlab-org/gitlab!30519

doc/.vale/gitlab/SubstitutionWarning.yml

+---
+# Warns against using common shorthand for terms.
+# For substitutions flagged as errors, see Substitutions.yml
+#
+# For a list of all options, see https://errata-ai.github.io/vale/styles/
+extends: substitution
+message: 'If possible, use "%s" instead of "%s".'
+link: https://about.gitlab.com/handbook/communication/#top-misused-terms
+level: warning
+ignorecase: true
+swap:
+  admin: administrator
+  config: configuration
+  distro: distribution
+  info: information
+  repo: repository

doc/.vale/gitlab/Substitutions.yml

 ---
 # Checks for use of some of the top misused terms at GitLab.
+# For substitutions only flagged as warnings, see SubstitutionWarning.yml
 #
 # For a list of all options, see https://errata-ai.github.io/vale/styles/
 extends: substitution