cosmetic changes to LLVM coding standards

Hi Chris,

I was reading the LLVM coding standards and noticed some typos &
formatting nits. Please see for
my proposed fix.

Most of changes are local and cosmetic. The only bigger change I made
is to group the sections about iostream and raw_ostream together, as
they are logically related. I had to edit the text a little bit after
the move, in order to reduce the repetition.

The patch is also attached to this message. Would you please take a
look? Thanks!

coding-standards.patch (11.4 KB)

Looks great! Applied in r119515, thanks!