docs(cli): add worldgen to newdocs

next-docs/pages/cli/worldgen.mdx

@@ -1 +1,35 @@
 # mud worldgen
+
+Autogenerate the MUD World interface based on Systems registered in the World.
+
+Use the `System`s under `src`<sup>1</sup> to generate the Solidity interface definitions for those `Systems` and put them in `src/codegen/world`.
+Also, create `src/codegen/world/IWorld.sol` which imports all the `System` interfaces.
+
+(1) By default this is any file that ends with `...System.sol`, for example `IncrementSystem.sol`.
+However, in the config file you can specify additional `System`s, under `systems`, as well as exclude files that end in `..System.sol`, by putting them under `excludeSystems`.
+
+
+## Sample usage
+
+```sh copy
+pnpm mud worldgen
+```
+
+## Options
+
+These are the command line options you can specify on `mud worldgen`:
+
+| Option         | Meaning                                                       | Type    | Default value   |
+| -------------- | ------------------------------------------------------------- | ------- | --------------- |
+| `--version`    | Show version number                                           | boolean | `false`         |
+| `--configPath` | Path to the config file                                       | string  | `mud.config.ts` |
+| `--clean`      | Clear the worldgen directory before generating new interfaces | boolean | `true`          |
+| `--help`       | Show help                                                     | boolean | `false`         |
+
+## Debugging
+
+To generate debug messages, use this command:
+
+```sh copy
+export DEBUG=mud:common:codegen
+```