<!-- Automatically generated... --> warning at the begining of each .xx.html file

[Kaloian Doganov]

Does this warning message needs to be defined differently for every
single team (langauge), or will be one generic English message for all
files, regardless of their main language?

If it is just one message, it can be hardcoded in the Scheme scripts, in
the GNUmakefile or in a dedicated well-known file.  If it has to be
customizable by the language teams, then we could use the generic.xx
approach.