add auto labeler

.github/label.yml

@@ -0,0 +1,2 @@
+japanese-translation:
+  - "**"

.github/workflows/autolabeler.yml

@@ -0,0 +1,15 @@
+
+name: Labeler for japanese-translation
+on:
+  pull_request:
+    branches:
+      - japanese-translation
+
+jobs:
+  label:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/labeler@v2
+        with:
+          repo-token: "${{ secrets.GITHUB_TOKEN }}"
+          configuration-path: ".github/label.yml"