[Chicken-users] Monad Egg updated, lots of docs added

[Daniel Leslie]

Please see the Wiki for complete details:
https://wiki.call-cc.org/eggref/4/monad

In short: some time ago I fleshed out the available monads with various utility functions that are generally excepted as being available for them. In the process I wrote a slew of usage examples, which should help those trying to understand what they're for and how they're used.

Have at it!

-Dan