Create find-unused.yml

Author: rustagir

.github/workflows/find-unused.yml

@@ -0,0 +1,15 @@
+name: Find Unused Files
+
+on:
+  pull_request:
+    paths:
+      - "source/**"
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: cbush/docdoctor/actions/find-unused@main
+        with:
+          source: ./source