doc: fix spelling

Fix various typos and spelling mistakes in the documentation

PR-URL: https://github.com/libuv/libuv/pull/17
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
unix, windows: fix typos in comments

Fix various typos and spelling mistakes in comments.
Does not affect any code, just changes comments.

PR-URL: https://github.com/libuv/libuv/pull/17
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>