doc: remove trace2 from InteractivePlotter documentation
doc: remove trace2 from InteractivePlotter documentation

As far as I can see, this was introduced in 584f88debf51 ("doc: Add
Documentation for Interactive Plotting") but never used.

sinkap/trappy,joelagnel/trappy,ARM-software/trappy,ARM-software/trappy,ARM-software/trappy,ARM-software/trappy,bjackman/trappy,bjackman/trappy,sinkap/trappy,joelagnel/trappy,sinkap/trappy,sinkap/trappy,bjackman/trappy,joelagnel/trappy,bjackman/trappy,joelagnel/trappy