Add PR labeler with pull_request_target

.github/labeler.yml

@@ -0,0 +1,16 @@
+# changes to documentation generation
+"area/doc-gen": doc/**/*
+
+# changes to the core Go cobra lib package
+"area/lib": ./*.go
+
+# changes to the Cobra CLI
+"area/cli": cobra/**/*
+
+# changes to Github workflows
+"area/github": .github/**/*
+
+# changes to shell completions
+"area/*sh completion":
+  - ./*completions*
+

.github/workflows/labeler.yml

@@ -0,0 +1,12 @@
+name: "Pull Request Labeler"
+on:
+- pull_request_target
+
+jobs:
+  triage:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/labeler@v3
+      with:
+        repo-token: "${{ github.token }}"
+