feat: add ci concurrency to doc building

.github/workflows/docs.yml

@@ -7,6 +7,10 @@ on:
     branches:
       - master
 
+concurrency:
+  group: docs-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   deploy:
     runs-on: ubuntu-latest