add luacheck action

.github/workflows/luacheck.yml

@@ -0,0 +1,18 @@
+name: luacheck
+
+on: [push, pull_request]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    steps:
+    - uses: actions/checkout@v2.3.4
+    - name: apt
+      run: sudo apt-get install -y luarocks
+    - name: luacheck install
+      run: luarocks install --local luacheck
+    - name: luacheck run
+      run: $HOME/.luarocks/bin/luacheck ./

readme.md

@@ -1,6 +1,9 @@
 
 controls library for minetest
 
+![](https://github.com/mt-mods/controls/workflows/luacheck/badge.svg)
+
+
 used by https://github.com/Arcelmi/minetest-bows.git
 
 Original repo: https://github.com/Arcelmi/minetest-controls