Avoid use branch for example workflows (#1231)

Author: ad-m

content/actions/reference/workflow-syntax-for-github-actions.md

@@ -446,7 +446,7 @@ steps:
     uses: monacorp/action-name@main
   - name: My backup step
     if: {% raw %}${{ failure() }}{% endraw %}
-    uses: actions/heroku@master
+    uses: actions/heroku@1.0.0
 ```
 
 #### **`jobs.<job_id>.steps.name`**
@@ -492,7 +492,7 @@ jobs:
     steps:
       - name: My first step
         # Uses the default branch of a public repository
-        uses: actions/heroku@master
+        uses: actions/heroku@1.0.0
       - name: My second step
         # Uses a specific version tag of a public repository
         uses: actions/[email protected]