add help/suggestions on people wishing to reproduce benchmarking tests

[eyberg]

have had multiple people reach out recently about this and there are a ton of easily fixable setup issues that would throw benchmarks off:

• ensure hardware accel is on (on by default but could be off if in a vm)
• ensure using tap/bridge otherwise default to slow user-mode
• ensure on same subnet, ensure same instance type
• use wrk over ab for http req/sec as ab is single-thread, use keep-alive
• do not test on a cloud vm - test as a cloud vm (eg: use 'instance create' not 'ops run' on cloud)

obviously a ton of other issues people will run into but these are the most common ones

[eyberg]

should show some examples of using iperf && iperf3