Proof reading corrections

This is a collection of suggested edits based on a first read-through of most of the doc.  I've included each fix in a separate commit so just let me know which ones you want to accept/drop and I can rebase to clean things up before you merge.

I'm not positive about the oaep change but the original statement appears to be incorrect.

The 'mod p' change may just be a matter of your desired notation (ie. the equation holds all mod p).
I have difficulty believing I ever got this wrong, but you are absolutely correct.