Improve development(7):

• Use Fx when referring to FreeBSD.
• Use Ql instead of Cm for command invocations.
• Remove some redundant Pp macros.
• Use a literal indented Bd instead of a series of Dl macros.

Submitted by: 0mp@
Reviewed by: eadler@
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D15126