extended documentation for catchException

[robkuz]

some clarification on the usage of catchException (hopefully)

[paf31]

I'm not sure if this adds anything, but the use of "Monad" is probably not what you intended. The only monad in use here is Eff (err :: EXCEPTION | eff), so you might say "in the Eff monad" instead. Note, the function arguments are not monads, since only type constructors can be monads, not values.

[paf31]

For future reference, for documentation updates, please update the source code and run pulp docs, instead of modifying the Markdown files directly.

[robkuz]

OK. I will remember the pulp docs thing the next time.
concerning the terminology - I am sure its wrong/not fitting. Much to much of a newbie to get it right yet.
However the gist of my PR was to have an example that a) actually throw an exception and that b) could be easily copied into a file and compiled/run and then can be used as an sandbox for further experiments.