[LyX/master] DocBook: add a parameter to change the namespace prefix for MathML.

[Pavel Sanda]

On Tue, Mar 23, 2021 at 11:25:55PM +0100, Thibaut Cuvelier wrote:
> I have pushed a new section in d0120078fd. I think the most important
> points for the user are documented there. Comments welcome :)!

Hmm, even after reading about the prefix options I have no clue in what
conditions or context should I choose either of them... 

Pavel