feat(ga-misc-check-prettier): add github action to check prettier

.github/workflows/ga-misc-check-prettier.yml

@@ -0,0 +1,26 @@
+name: 'Prettier check'
+on:
+  pull_request:
+    branches:
+      - master
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    name: Run prettier on changed files
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0  # OR "2" -> To retrieve the preceding commit.
+
+      - name: Get all changed *.md file(s) 
+        id: changed-md
+        uses: tj-actions/changed-files@v35
+        with:
+          files: |
+            **/*.md
+
+      - name: Run step if any *.md file(s) changed 
+        if: steps.changed-md.outputs.any_changed == 'true'
+        run: |
+          npm i -g prettier
+          npx prettier -c ${{steps.changed-md.outputs.all_changed_files}}