[Live-demo] presentation.rst files

[Activity Workshop]

Just a quick question: can the en/presentation.rst file (and all the
translations) be deleted now?
It doesn't seem to make much sense to refer to a 2010 blogpost talking about
"lightening" (ouch) any more.

Also the en/presentation/index.html will need to be updated, presumably deleting
the "New in 9.5?" section and removing the applications which will no longer be
part of 11.0.  Although I don't know if the list of included applications has
been finalised yet.