document that setting RelayBandwidthRate changes RelayBandwidthBurst
when setting RelayBandwidthRate I didn't expect that will also change
RelayBandwidthBurst (default: 0 according to the manpage)
I only realized it after connecting to the relay via Nyx. Nyx showed that
RelayBandwidthBurst is at the same value as RelayBandwidthRate,
even though RelayBandwidthBurst does not appear in the torrc file
**Trac**:
**Username**: a_p
issue