remove dechartered working group (#1213)
remove dechartered working group (#1213)

The only top-level working group has been dechartered and superseded by
the Community Committee. Remove information about the dechartered
working group. For that matter, since there aren't any top-level
working groups, remove text identifying that there are two different
types of working groups (since, at the current time anyway, there is
only one type of working group that actually exists).
yous/new.nodejs.org,phillipj/new.nodejs.org,nodejs/new.nodejs.org,nodejs/new.nodejs.org,phillipj/new.nodejs.org,yous/new.nodejs.org