editors/nvi-devel: Deprecate in favor of editors/nvi2

nvi-devel is based on a 2015 tarchive with several port patches
while nvi2 is an active project with over 600 commits since 2011
(including a pull request I submitted just today) that currently
has no port patches.

Please let me know if nvi-devel does anything that nvi2 does not
and I will attempt to rectify.