Use ordinary paragraph for sv.h reference in perlguts

Howdy,

perlguts uses a verbatim paragraph for the following paragraph:

> See the sv.h header file for more details.

The attached patch makes it use an ordinary paragraph instead (and use
the F formatting code for sv.h).

-- 
Matt                                                 http://ftbfs.org/

• Use ordinary paragraph for sv.h reference in perlguts by Matt Kraai