Configuration documentation: remove deprecated/wrong [core]max_reschedules entry (#2692)
Configuration documentation: remove deprecated/wrong [core]max_reschedules entry (#2692)

The configration doc contains entry on `[core]max_reschedules`,
which is not only deprecated (in favor of `[worker]max_reschedules`)
but also wrong: the correct (but deprecated) config key is
`[core]worker-max-reschedules`.
Better get rid of this all together and just keep `[worker]max_reschedules`
spotify/luigi,adaitche/luigi,jamesmcm/luigi,jamesmcm/luigi,riga/luigi,dlstadther/luigi,spotify/luigi,spotify/luigi,PeteW/luigi,dlstadther/luigi,rayrrr/luigi,jamesmcm/luigi,riga/luigi,dlstadther/luigi,riga/luigi,PeteW/luigi,dlstadther/luigi,PeteW/luigi,jamesmcm/luigi,adaitche/luigi,spotify/luigi,adaitche/luigi,rayrrr/luigi,rayrrr/luigi,rayrrr/luigi,PeteW/luigi,adaitche/luigi,riga/luigi