Add networking details to the readme

[mattstauffer]

See #170

[mattstauffer]

@danielebarbaro I was thinking something along the lines of:

1. sharing that it is automatically added to a network named takeout
2. Sharing the basics about how the aliasing and base aliasing works
3. (optional) giving an example of how to use them in another Docker container using their aliases.

If any of this isn't clear I'll be happy to explain