doc: don't recommend domains for error handling
doc: don't recommend domains for error handling

Remove the suggestion to use domains for exception handling. Add clarity
to "unhandledException".

Fixes: https://github.com/nodejs/io.js/issues/2055
PR-URL: https://github.com/nodejs/io.js/pull/2056
Reviewed-By: Trev Norris <9cb5491eb5770dd8e0bf77a8a0335abf5f0488c5@gmail.com>
Reviewed-By: Chris Dickinson <711c73f64afdce07b7e38039a96d2224209e9a6c@neversaw.us>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node