Add explicit permissions block to web-example-ghpages.yml

Author: BYK

.github/workflows/web-example-ghpages.yml

@@ -4,6 +4,10 @@ on:
   release:
     types: [published]
 
+permissions:
+  contents: write
+  pull-requests: write
+
 jobs:
   build:
     runs-on: ubuntu-latest