[Pkg-mailman-hackers] Fixing #280926

[Héctor García Álvarez]

Hi all

I would like to fix #280926 adding a link on /usr/bin as mm_change_pw
and adding the proposed man page.
What do you think?

Regards,

Héctor

P.D: We can start slowly creating links as proposed by Lionel on this
bug, to all binaries at /var/lib/mailman/bin/ avoiding the namespace
pollution using the mm_ prefix on the links.
I would only links the binaries with man page.