add checkGenCutTool script and MD report

@kreps I was checking which RareDecays DEC files are affected by the -> vs => bug and thought about pushing here a simple script and MarkDown report I produced
This just gives a rough idea of the scale of the problem, and the script could be further tuned
Let me know if you think this could be useful to other WG as well

There are a mixture of cases where the issue appears on the mother and/or on the intermediate daughters, but I am not sure if both are relevant