Bug#829159: mention what will happen when colrm used with no args

[積丹尼 Dan Jacobson]

Package: bsdmainutils
Version: 9.0.10
Severity: wishlist
File: /usr/share/man/man1/colrm.1.gz

Mention what will happen if both start and stop are omitted.
E.g.,
$ date | colrm