doc: Move pool=... syntax inside of single quotes

When specifying caps, the entire 'allow ...' bit needs to be in the
single quotes, including the pool= part.

Signed-off-by: Travis Rhoden <trhoden@gmail.com>
doc: Update create example to use 'allow ' syntax

The ceph auth get-or-create example here is the only place on the
page that does not use 'allow <perms.' syntax.  I found that
confusing.  Update to use allow and single quotes.

Signed-off-by: Travis Rhoden <trhoden@gmail.com>
Merge pull request #56 from trhoden/doc_cephx

Make cephx key creation syntax consistent

Reviewed-by: Sage Weil <sage@inktank.com>