Merge pull request #622 from cgswords/patch-2

Added a usage example for local builds

README.md

@@ -350,16 +350,23 @@ $ rustup target add i686-pc-windows-gnu # this one's installed by default
 [MinGW/MSYS2 toolchain]: https://msys2.github.io/
 [vs]: https://www.visualstudio.com/downloads
 
-## Working with custom toolchains
+## Working with custom toolchains and local builds
 
 For convenience of developers working on Rust itself, `rustup` can manage
-local builds of the Rust toolchain. To teach `rustup` about your build
-just run:
+local builds of the Rust toolchain. To teach `rustup` about your build,
+run:
 
 ```
 $ rustup toolchain link my-toolchain path/to/my/toolchain/sysroot
 ```
 
+For example, on Ubuntu you might clone `rust-lang/rust` into `~/rust`, build it, and then run:
+
+```
+$ rustup toolchain link myrust ~/rustg/x86_64-unknown-linux-gnu/stage2/
+$ rustup default myrust
+```
+
 Now you can name `my-toolchain` as any other `rustup`
 toolchain. Create a `rustup` toolchain for each of your
 `rust-lang/rust` workspaces and test them easily with `rustup run