Docs: adding sections
I would like to add to the readme docs.  

For starters, a simple install section wouldn't hurt for newcommers. Specifically, should the current recommendation be to install by using `nimble install jester#head` to ensure you have the latest fixes? Right now if you do `nimble install jester` error routes like the one below don't work:
```nim
error Http404:
    resp "not found"
```