Document how to build the protocol buffer bindings

[#72801782]

Signed-off-by: Zach Robinson <[email protected]>

warden-protocol/README.md

@@ -5,9 +5,26 @@
 
 [tlr]: /README.md
 
+## Building
+Generating the protocol buffer bindings requires a protocol buffer compiler.
+If you're a homebrew user on the mac, you can use `brew install protobuf`; if
+you're using another platform, please visit the
+[protocol buffer project][protobuf] for information about how to download or
+build the compiler.
+
+Once you have `protoc` on your path:
+
+1. `bundle`
+1. `bundle exec rake build`
+
+## Testing
+
+Use `bundle exec rake spec` to execute the tests.
+
 ## License
 
 The project is licensed under the Apache 2.0 license (see the
 [`LICENSE`][license] file in the root directory of the repository).
 
 [license]: /LICENSE
+[protobuf]: https://code.google.com/p/protobuf