Minor $timeout doc cleanup

Minor cleanups on $timeout documentation

* Added a comma separator in the  statement
The return value of registering a timeout function is a promise`,` which will be resolved when the timeout is reached and the timeout function is executed.

* Removed the word `the` from the statement 
To cancel a the timeout request, call $timeout.cancel(promise).

* Used `whose` instead of `who's` in the following statement
fn – {function()} – A function, who's execution should be delayed.

* Italicized `false` in the statement
invokeApply(optional=true) – {boolean=} – If set to false skips model dirty checking, otherwise will invoke fn within the $apply block.

* Used a comma separator in the statement
Cancels a task associated with the promise. As a result of this`,` the promise will be resolved with a rejection.