Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r235317:

General mdoc(7) and typo fixes.

PR: 167776

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Now that lnc(4) is removed from the source tree, replace lnc0 in an example
with fxp0 (fxp(4) was chosen as it's also used in a couple of examples in
other man pages and as it has good grep(1)'ability).

Verify that SYNOPSIS section compiles.

(fast) ethernet -> (Fast) Ethernet

MFC after: 3 days

Replace all uses of the old netgraph constants NG_*LEN by the new
constants NG_*SIZ that include the trailing NUL byte. This change
is mostly mechanical except for the replacement of a couple of snprintf()
and sprintf() calls with strlcpy.

Slight correction to ng_etf man page and add it to the list
of man pages to install.

mdoc(7) police: cleanup.

Fix typos.

A node that allows ethernet type packets to be filtered to different
hooks depending on ethertype. Great for prototyping protocols.
connects to the lower and upper hooks of an ethernet type of node.

Obtained from: Monzoon Networks.
Thanks to Andre Oppermann, May 2001.