update README

Made 3 distinct steps, clarified packaging, moved running bot at end (not needed by most people), ensured correct capitations.

Diff is confusing; easier just to [read directly](https://github.com/tomByrer/libgrabber/blob/master/README.md)
I think it should be `and` not `that`. But I am not a native so not sure

`...servers and is responsible...`

`...servers that is responsible...`