On Emacs, if you hit enter on a package after running (M-x list-packages), there's usually a brief summary and a link to Github. After you install the package, you have lots of commands to access documentation. Here's some of them:

  C-h i: info manuals
  C-h ?: help for help 
  C-h F: help for commands
  C-h v: help for variables
  C-h f: help for functions
  C-h m: help for minor modes

That's a lot of help if you ask me!