[docs][ci] Updated examples check (#19792)

## Description 

Use existing action to filter change location.

## Test plan 

yolo

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:
- [ ] REST API:

.github/actions/diffs/action.yml

@@ -22,6 +22,9 @@ outputs:
   isMoveAutoFormatter:
     description: True when changes happened in MoveAutoFormatter code
     value: "${{ steps.diff.outputs.isMoveAutoFormatter }}"
+  isExamples:
+    description: True when changes happened in examples/ directory
+    value: "${{ steps.diff.outputs.isExamples }}"
 
 runs:
   using: composite
@@ -76,3 +79,5 @@ runs:
           - 'sui-execution/**'
         isMoveAutoFormatter:
           - 'external-crates/move/crates/move-analyzer/prettier-plugin/**'
+        isExamples:
+          - 'examples/**'

.github/workflows/docs-ci.yml

@@ -29,16 +29,12 @@ jobs:
       - name: Build
         run: pnpm build
         working-directory: ./docs/site
-      - name: Check for changes in the examples directory
-        id: check_changes
-        run: |
-          if git diff --name-only $GITHUB_EVENT_BEFORE $GITHUB_SHA | grep '^examples/'; then
-            echo "examplechanges=true" >> $GITHUB_ENV
-          else
-            echo "examplechanges=false" >> $GITHUB_ENV
-          fi
+      - name: Detect Changes
+        uses: './.github/actions/diffs'
+        id: diff
       - name: Notify Slack if examples directory changed
-        if: env.examplechanges == 'true' && github.event.action == 'opened'
+        needs: diff
+        if: needs.diff.outputs.isExamples
         uses: slackapi/[email protected]
         with:
           payload: |