Add concurrency key to publish/preview workflows (#527)

Author: penelopeysm

.github/workflows/preview.yml

@@ -7,6 +7,9 @@ on:
       - synchronize
       - closed
 
+concurrency:
+  group: docs
+
 jobs:
   build-and-preview:
     if: github.event.action == 'opened' || github.event.action == 'synchronize'

.github/workflows/publish.yml

@@ -7,6 +7,10 @@ on:
       - backport-v0.*
   workflow_dispatch: # manual trigger for testing
 
+concurrency:
+  group: docs
+  cancel-in-progress: true
+
 jobs:
   build-and-deploy:
     runs-on: ubuntu-latest