Nit in section 2.1.1 of httpbis-p1

As I said on the mic in SF:
Section 2.1.1 of part 1 is a bit too waffly about IP addresses, and
what it wants to say is already covered in the meaning of SHOULD
anyway.  So:

OLD
The use of IP addresses in URLs SHOULD be avoided whenever possible
(see [RFC1900]).

NEW
IP addresses SHOULD NOT be used in URLs (see [RFC1900]).

Technically, these say the same thing, so it's not a substantive
change.  But the second is in the active voice, and doesn't use the
waffly "whenever possible" phrase.

Barry