Add missing documentation

[luc-tielen]

The big picture of what I'm trying to do

Experimenting / trying out a small webapp that uses this library.

What I did

Tried to use some features in the library, started looking for docs to figure out how certain functions work.

What I Expected To Happen

Expected docs to be there for all functions, preferrably with examples.

What Actually Happened

Documentation was missing, quite a few functions have {-| -} as their 'documentation' in code. Ended up looking at actual code to figure out what was going on.