Use organization's LuaCheck workflow

.github/workflows/luacheck.yml

@@ -1,13 +1,10 @@
 name: luacheck
 on: [push, pull_request]
 jobs:
-  build:
+  luacheck:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
-    - 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 ./
+      - name: Checkout
+        uses: actions/checkout@master
+      - name: Luacheck
+        uses: lunarmodules/luacheck@master

README.md

@@ -14,8 +14,8 @@ It is primarily intended for mapgen v6, but it should work fine when used with m
 
 **Dependencies:** nothing, but if you don't use `minetest_game`, you'll need to supply some settings (see API.txt).
 
-**Recommends**: [Plantlife Modpack](https://github.com/minetest-mods/plantlife_modpack), 
-[More Trees](https://github.com/minetest-mods/moretrees)
+**Recommends**: [Plantlife Modpack](https://github.com/mt-mods/plantlife_modpack), 
+[More Trees](https://github.com/mt-mods/moretrees)
 
 **API**: This mod supplies a small number of very powerful functions. They are, briefly: