Fixing selenium build requirements
@@ -120,6 +120,7 @@ from https://github.com/facebook/watchman
* `java` and `jar` on the PATH (make sure you use `java` executable from JDK but not JRE)
* [Python 2.7](https://www.python.org/)
* `python` on the PATH (make sure it's Python 2.7, as buck build tool is not Python 3 compatible)
+* MacOS users should have XCode installed
Although the build system is based on rake, it's **strongly advised**
to rely on the version of JRuby in `third_party/` that is invoked by
