Try setting an environment variable to the list of files to be linted.

Author: stevepiercy

.github/workflows/test.yml

@@ -23,4 +23,7 @@ jobs:
           sudo snap install --edge vale
 
       - name: Run tests with make test
-        run: make test vale
+        run: |
+          echo "VALEFILES=$(find -L ./docs/ -type d \( -path ./docs/plone.restapi/lib/* -o -path "./docs/plone.restapi/performance/*" \) -prune -false -o -type f -name "*.md" -print)" >> $GITHUB_ENV
+#          make test
+          make vale ${{ env.VALEFILES }}