Re: pgbench doc fix

>> "prepared: use extended query protocol with reused prepared statements"
>
> I don't think this mouthful is useful in the --help output.  The
> existing wording gets the message across just fine, I think.  More
> details can be put in the reference page.

These suggestions are for the online doc page, and possibly an internal 
comment in the code.

The pgbench --help just states the 3 possible values and the say which is 
the default, and indeed cannot say much more.

-- 
Fabien.