Add example for aliases

[p-galligan]

I think it could be helpful to provide a link for how to create an alias in the readme.

"Note that this assumes your install of Python has python3 and pip3 aliases, which it should, especially if installed in a virtualenv."

Above could be obtuse for some.

[pobocks]

Fixed in 2cc0a71 by changing language to be less specific and suggest checking out docs.