docs: add lx check to tutorial

Author: Marc Jakobi

docs/tutorial/07-code-hygiene.md

@@ -6,6 +6,23 @@ title: Code Hygiene
 Code hygiene is the practice of writing code that is readable and maintainable.
 In this chapter, we'll let tools automatically clean up our code for us.
 
+## Type checks with LuaCATS annotations
+
+Lua is incredibly responsive when used for configuration or scripting, giving immediate feedback.
+But in the context of a project that needs to be maintained long-term, its dynamic typing casts
+shadows of unpredictability, making Lua projects susceptible to unexpected bugs at the wrong time.
+
+To help mitigate this, Lux provides a `lx check` command, which uses [emmylua_check](https://github.com/EmmyLuaLs/emmylua-analyzer-rust)
+to statically type-check your codebase based on [LuaCATS annotations](https://github.com/EmmyLuaLs/emmylua-analyzer-rust).
+
+The command will:
+
+1. Build your project and its dependencies if not done already.
+2. Generate workspace library entries for a [`.luarc.json` file](https://github.com/LuaLS/lua-language-server/wiki/Configuration-File).
+3. Run the static checker.
+
+<!--TODO: show output of lx check and fix the errors that exist there-->
+
 ## Linting with `lx lint`
 
 Linting is the process of analyzing code for potential errors and stylistic issues (lines too long, unused variables, etc.).