Adding "workbook/" to the list of checked folders

Author: spier

.github/workflows/vale.yml

@@ -22,7 +22,7 @@ jobs:
       uses: errata-ai/vale-action@reviewdog
       with:
         # the folders to run the checks for
-        files: '["docs/","introduction/", "trusted-committer/", "contributor/", "product-owner/", "project-leader/"]'
+        files: '["docs/","introduction/", "trusted-committer/", "contributor/", "product-owner/", "project-leader/", "workbook/"]'
         # we want to check all files in the folders listed above, but exclude
         # a) any files in subfolders (these are translations)
         # b) any '-script.asciidoc' files