allow worflow dispatch on docs deploy

Author: hturner

.github/workflows/build-mkdocs-website.yml

@@ -15,7 +15,9 @@ permissions:
 
 jobs:
   build-and-deploy:
-    if: ${{github.event_name == 'pull_request' && github.event.action == 'closed' && github.event.pull_request.merged == true}}
+    if: |
+      github.event_name == 'workflow_dispatch' ||
+      (github.event_name == 'pull_request' && github.event.pull_request.merged == true)
     runs-on: ubuntu-latest
 
     steps: