Lint using Gixy

Closes #285

.github/workflows/lint.yml

@@ -0,0 +1,16 @@
+# https://help.github.com/actions
+
+name: Lint
+
+on: [push, pull_request]
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2.3.4
+
+      - name: Lint configuration using Gixy
+        uses: docker://yandex/gixy:latest
+        with:
+          args: /github/workspace/nginx.conf