readme: maps update

[missinglink]

I would like to soften the language a little.

I think the 'mandatory' text is sufficient enough in a legal sense to indicate the license requirements.

I'd prefer to avoid using language that could be perceived as 'strern' or 'disciplinary'.

[orangejulius]

You could even change "mandatory" to "required". That feels less like a judgement and more like a statement to me.

[missinglink]

As discussed offline, mandatory is fine here.