Remove outdated information from the netperf webpage.

The netperf webpage has not been updated in quite some time. Most updates
regarding machine allocations are happening on the wiki nowadays. It does not
make sense to keep the information here, so remove the section and replace it
with a reference to the wiki instead.

The config and news section has also been largely left alone for years. Remove
it as well as it is unlikely that someone will be posting updates there any
time soon.

Reported by: emaste (on IRC)
Approved by: emaste
Differential Revision: https://reviews.freebsd.org/D19959