Update command line section for config

The old version uses instructions for `freeseer-config`, like `--reset` etc, which isn't supported anymore.

Added some example help output because it's easier than describing all the commands and options.

![image](https://cloud.githubusercontent.com/assets/497458/4381863/fbb0d73a-437c-11e4-8314-1ab2d859d2b9.png)

Closes #595