Add some extra steps to the asdf uninstall to help minimize problems with chef environments.

docs/developer-setup.md

@@ -83,6 +83,8 @@ $ brew uninstall asdf --force
 $ # open a new terminal before continuing...
 ```
+In addition to removing references to loading asdf in your rc files, you may need to remove compile time environment variables such as LDFLAGS, RUBY_CONFIGURE_OPTS, CPPFLAGS, and PKG_CONFIG_PATH.
+
 ### Step 3.2: Install `rtx`
 [`rtx`](https://github.com/jdx/rtx) is a polyglot runtime manager. It is compatible with [`asdf`](https://asdf-vm.com/) and relies on the `asdf` plugin ecosystem, but has some advantages over `asdf` in that it generally requires fewer shims and is faster.