Proper use of replaced_by

[Mojca Miklavec]

Hello,

I've been told to use mysql5-server-devel as an example of how to
properly replace  a port. I now see that
    https://trac.macports.org/wiki/PortfileRecipes#replaced-by
suggest to do it in a slightly different way. In any case it doesn't
mention the obsolete PortGroup.

Should the recipe be updated perhaps?

Mojca