chore: add `npm run build:schema` to the doc generation action

The github action that generates the documentation fails currently due
to the fact that it's expecting the generated schema to exist, but it
does not exist unless it's explicitly built.

This commit adds `npm run build:schema` to the workflow action.

Signed-off-by: Lance Ball <lball@redhat.com>

.github/workflows/api-docs.yaml

@@ -11,7 +11,7 @@ jobs:
         uses: actions/checkout@v2
       -
         name: Generate API documentation
-        run: npm install && npm run generate-docs
+        run: npm install && npm run build:schema && npm run generate-docs
       -
         name: Deploy to GitHub Pages
         if: success()