Update 'discouraged'
Update 'discouraged'

We renamed a number of labels, and some of those renames
require that we regenerate the 'discouraged' file.

Signed-off-by: David A. Wheeler <9ae72d22d8b894b865a7a496af4fab6320e6abb2@dwheeler.com>

metamath/set.mm,metamath/set.mm,metamath/set.mm