doc: update changelog for io.js v3.3.0

Notable changes:

* build: Add a --link-module option to configure that can be used to
  bundle additional JavaScript modules into a built binary
  (Bradley Meck) #2497
* docs: Merge outstanding doc updates from joyent/node
  (James M Snell) #2378
* http_parser: Significant performance improvement by having
  http.Server consume all initial data from its net.Socket and parsing
  directly without having to enter JavaScript. Any 'data' listeners on
  the net.Socket will result in the data being "unconsumed" into
  JavaScript, thereby undoing any performance gains.
  (Fedor Indutny) #2355
* libuv: Upgrade to 1.7.3 (from 1.6.1), see
  https://github.com/libuv/libuv/blob/v1.x/ChangeLog for details
  (Saúl Ibarra Corretgé) #2310
* V8: Upgrade to 4.4.63.30 (from 4.4.63.26) (Michaël Zasso) #2482

cherry-picked from v3.x @ 1a6e52db

PR-URL: https://github.com/nodejs/node/pull/2653


Reviewed-By: cjihrig - Colin Ihrig <cjihrig@gmail.com>