workflows docs: check docs is building on push to master

Author: amorison

.github/workflows/docs.yml

@@ -2,6 +2,8 @@ name: docs
 
 on:
   push:
+    branches:
+      - master
     tags:
       - 'v[0-9]+.[0-9]+.[0-9]+'
   pull_request:
@@ -31,7 +33,7 @@ jobs:
 
   deploy:
     needs: build
-    if: ${{ github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/tags/v') }}
+    if: ${{ github.event_name == 'workflow_dispatch' || startsWith(github.ref, 'refs/tags/v') }}
     permissions:
       pages: write
       id-token: write