improve the 're' manpage by correcting typos and rewording

[Matthias Lang]

Hi,

git fetch git://github.com/matthiasl/otp.git re-manpage-cleanup

I took a couple of passes through the manpage and fixed all the typos
I saw. I also shortened some sentences.

(Branch looks wonky because I just learned that 'git commit --amend'
doesn't work if you've already done a 'git push'. So I merged and pushed
again.)

Matt