Added basic instructions on usage

Provided instructions to use in the main script.js
There is also a way to use this via console, but I didn't write how to use that method.
All options are optional.
Fixed misspelling
Added log levels option based on socket.io log levels
Merge branch 'loglevel' of https://github.com/ZombieHippie/devreload into loglevel
Merge pull request #2 from ZombieHippie/loglevel

Added loglevel option support