Add GitHub workflow

.github/workflows/build.yml

@@ -0,0 +1,11 @@
+on: [push, pull_request]
+name: build
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - name: lint
+        uses: Roang-zero1/factorio-mod-luacheck@master
+        with:
+          luacheckrc_url: ""

README.md

@@ -44,4 +44,4 @@ Minetest or are using node formspecs.
 such as hypertext and background9 so the formspec will still work properly with
 newer clients.*
 
- [formspec_ast]: https://git.minetest.land/luk3yx/formspec_ast
+ [formspec_ast]: https://content.minetest.net/packages/luk3yx/formspec_ast