Remove instructions for virtualenvwrapper

I haven't tested them, and I don't think virtualenvwrapper is particularly necessary / helpful.

README.md

@@ -39,25 +39,14 @@ Want to hack on mozregression ? Cool!
 ### Installing dependencies
 
 To make setup more deterministic, we have provided requirements files to use a known-working
-set of python dependencies. You can install these inside a virtual environment
-to create a development environment.
+set of python dependencies. From your mozregression checkout, you can install these inside 
+a virtual development environment.
 
 This is a two step process:
 
-1. If you don't have them already, install [virtualenv](https://virtualenv.pypa.io/en/stable/)
-   or [virtualenvwrapper](https://virtualenvwrapper.readthedocs.org/en/latest/).
+1. If you don't have it already, install [virtualenv](https://virtualenv.pypa.io/en/stable/).
 
-2. Install dependencies:
-
-With virtualenvwrapper:
-
-```bash
-mkvirtualenv -p /usr/bin/python3 mozregression
-pip install -r requirements/all.txt
-pip install -e .
-```
-
-Or with virtualenv: ::
+2. Activate virtualenv and install dependencies:
 
 ```bash
 virtualenv -p /usr/bin/python3 venv