DOC: explain more clearly how to change the timer
DOC: explain more clearly how to change the timer

spacetelescope/asv,qwhelan/asv,spacetelescope/asv,qwhelan/asv,airspeed-velocity/asv,qwhelan/asv,spacetelescope/asv,airspeed-velocity/asv,spacetelescope/asv,qwhelan/asv,airspeed-velocity/asv,airspeed-velocity/asv