Improve documentation

[XayOn]

Detailed Description

Current 3.0.0a documentation is mostly missing.

Possible Implementation

• [ ] A wiki about supported sites would be preferable.
• [x] Update readme with usage
• [x] Update readme with libtorrent instalation instructions to stream
• [x] Update readme with better jackett instructions
• [x] Add TOC

[XayOn]

The WIKI does not seem like that a good idea...