Add a callout box about ntuples filenames in ganga script and DaVinci scripts

[xlr91]

One of the more common first mistakes on ganga is that if the ntuple output filename in ntuple_options.py is different than the one defined in the ganga file first-job.py, ganga gets confused (I think) and ends up not producing any tuples in the output file.

eg. if the jobs are defined as follows:
first-job.py

j.outputfiles = [LocalFile('gangaoutput.root')]

ntuple_options.py

DaVinci().TupleFile = 'DVntuple.root'

No root output would be produced from ganga, at least from my experience

Maybe it would be a good idea to have some kind of popout box to point out this so that people dont repeat the same mistake I did and be disappointed when theres no root files after waiting for the job to finish? :D