Revert "Delete main.yml"

This reverts commit 037cd96e71.

.github/workflows/main.yml

@@ -0,0 +1,17 @@
+
+name: Simple CI
+
+on: [pull_request]
+
+jobs:
+  run-ci:
+    name: Build Frontend
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions/setup-node@v1
+      with:
+        node-version: '12.x'
+    - run: npm install
+    - run: npm run lint
+    - run: make