add contributing section to readme

README.md

@@ -56,4 +56,16 @@ run lua() {
     -- Lua code goes here
     return "Hello, Lua!";
 };
-```
+```
+
+### Full Grammar
+The full grammar can be found [here](./grammar.md).
+
+## Contributing
+
+Pull requests are welcome. For major changes, please open an issue first
+to discuss what you would like to change.
+
+Please make sure to update tests as appropriate.
+
+**Note that this repository only contains the parser and transpiler to a secondary representation. The compilation to a Minecraft datapack is located in the [shulkerbox](https://github.com/moritz-hoelting/shulkerbox) repository. Please indicate if pull requests for this repository require pull requests for the shulkerbox repository**