Adding {FUZZY} to username in sample path

In the OS X RVM install directions, we've grayed out version numbers so that users won't be concerned with matching these exactly.

![screen shot 2014-09-28 at 8 40 02 pm](https://cloud.githubusercontent.com/assets/59535/4437140/94d474ee-478d-11e4-84e6-32f7ce58a5fa.png)

I suggest we do the same with `alex`, to reduce confusion.