Add a license header check

Signed-off-by: Stephen Kitt <skitt@redhat.com>

.github/workflows/linting.yml

@@ -50,6 +50,16 @@ jobs:
       - name: Run golangci-lint
         run: make golangci-lint
 
+  headers:
+    name: License Headers
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repository
+        uses: actions/checkout@v2
+
+      - name: Check License Headers
+        uses: nilp0inter/search-legal-headers@v0.1.0
+
   markdown-link-check:
     name: Markdown Links (modified files)
     runs-on: ubuntu-latest

.legal.json

@@ -0,0 +1,4 @@
+{
+  "**/*.go": "Licensed under the Apache License, Version 2.0 (the \"License\");\nyou may not use this file except in compliance with the License.\nYou may obtain a copy of the License at\n\n    http://www.apache.org/licenses/LICENSE-2.0\n\nUnless required by applicable law or agreed to in writing, software\ndistributed under the License is distributed on an \"AS IS\" BASIS,\nWITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\nSee the License for the specific language governing permissions and\nlimitations under the License.\n",
+  "LICENSE": "Apache License"
+}