1.0.16: Convert markdown footnotes into crefs (note that these are only visible if the pi "comments" is set to yes).
The anchor is taken from the markdown footnote name.  The source, if it is really needed, can be supplied by an IAD, as in (first example with ALD):

    {:cabo: source="cabo"}

    (This section to be removed by the RFC editor.)[^1]{:cabo}

    [^1]: here is my editorial comment

    Another questionable paragraph.[^2]{: source="observer"}

    [^2]: so why not delete it

Note that XML2RFC v2 doesn't allow structure in crefs. If you put any, you get the escaped verbatim XML...