Create validate-swagger.yml

.github/workflows/validate-swagger.yml

@@ -0,0 +1,13 @@
+name: Validate API swagger documentation
+on: [push, pull_request]
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Validate openAPI
+      id: validate
+      uses: mbowman100/swagger-validator-action@2.0
+      with:
+        files: docs/tdlight-api-openapi.yaml