update how-to note
def allconfs and talksdata for easier access.

The allconfs vector contains all the tagsouped conference data with args ready
for passing to data-ify.

talksdata contains a vector of the results of data-ify for all conferences.
Initial work on 'collect-val and 'coalesce-confs.

coalesce-confs will extract conferences and speakers from the talks.