Typo fix + note calling then() multiple times ok

Hat tip Evan Goer and Marco Asbreuk, respectively. I hope I spelled
Marco's name right.
Merge branch 'live-docs' of git://github.com/juandopazo/yui3 into juandopazo-live-docs
Adjust Promise's component.json data and whitespace
Fix typos and whitespace in Promises user guide and examples
Merge pull request #5 from ericf/juandopazo-live-docs

Some fixes for Promise's user guide and examples