currently hysteresis-secs only works when the demuxer-max-bytes fills
up. but it's possible for the cache-secs/demuxer-readahead-secs to be
reached first.
in those cases, hysteresis-secs doesn't work and keeps buffering
non-stop. but the goal of this option was to save power by avoiding
non-stop buffering so go ahead and make it respect cache-secs as well.
additionally remove some redundant repetition from the docs.
NRK
3789f1a387