README - add DistComp plots of progress of campaigns

Note that so far we only have such plots for Stripping.

As per our email exchanges, @cbozzi, @fredi, @ngrieser, @avenkate, @nskidmor. Cc @abertoli and @shunan FYI.

For completeness - I have sent some suggestions for improvements to the plots. Watch out for this space (meaning the link).

Thank you again @cbozzi for making the plots available.