Update stale contributor documentation

CONTRIBUTING.md

@@ -13,12 +13,27 @@ Code contributions are welcome for features and bugs that have been reported in
 
 You'll want these tools to work on Rojo:
 
-* Latest stable Rust compiler
+* Rust 1.88 or newer
   * Rustfmt and Clippy are used for code formatting and linting.
-* Latest stable [Rojo](https://github.com/rojo-rbx/rojo)
 * [Rokit](https://github.com/rojo-rbx/rokit)
 * [Luau Language Server](https://github.com/JohnnyMorganz/luau-lsp) (Only needed if working on the Studio plugin.)
 
+Rokit installs the pinned Rojo, Selene, StyLua, Lune, and run-in-roblox versions listed in [`rokit.toml`](rokit.toml):
+
+```bash
+rokit install
+```
+
+Before opening a pull request, run the relevant checks:
+
+```bash
+cargo test
+cargo fmt -- --check
+cargo clippy
+stylua --check plugin/src
+selene plugin/src
+```
+
 When working on the Studio plugin, we recommend using this command to automatically rebuild the plugin when you save a change:
 
 *(Make sure you've enabled the Studio setting to reload plugins on file change!)*
@@ -29,7 +44,7 @@ bash scripts/watch-build-plugin.sh
 
 You can also run the plugin's unit tests with the following:
 
-*(Make sure you have `run-in-roblox` installed first!)*
+*(If you are not using Rokit, make sure you have `run-in-roblox` installed first!)*
 
 ```bash
 bash scripts/unit-test-plugin.sh
@@ -49,7 +64,7 @@ Please file issues and we'll try to help figure out what the best way forward is
 
 ## Local Development Gotchas
 
-If your build fails with "Error: failed to open file `D:\code\rojo\plugin\modules\roact\src`" you need to update your Git submodules.
+If your build fails with an error about a missing path under `plugin/Packages`, such as `plugin/Packages/Roact`, you need to update your Git submodules.
 Run the command and try building again: `git submodule update --init --recursive`.
 
 ## Pushing a Rojo Release