[ issue 1356 ] NameKind commands in agda.sty enforce no math spacing

Cherry-picked from https://github.com/agda/agda/commit/90c8becd4b8d22fabfa9c76deabc77f0402e0e53.
[ issue 1356 ] Added missing documentation
Merge branch 'maint-2.4.2'

Conflicts:
	src/data/agda.sty