doc: util: document --trace-deprecation
doc: util: document --trace-deprecation

Document the --trace-deprecation flag and the `process` properties that
affect util.deprecate().

Fixes: https://github.com/iojs/io.js/issues/190
PR-URL: https://github.com/iojs/io.js/pull/191
Reviewed-By: Jonathan Ong <b1c1d8736f20db3fb6c1c66bb1455ed43909f0d8@jongleberry.com>

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