git-cvsimport: use a lowercase "usage:" string

Make the usage string consistent with Git.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-cvsimport.perl

@@ -38,7 +38,7 @@ sub usage(;$) {
 	my $msg = shift;
 	print(STDERR "Error: $msg\n") if $msg;
 	print STDERR <<END;
-Usage: git cvsimport     # fetch/update GIT from CVS
+usage: git cvsimport     # fetch/update GIT from CVS
        [-o branch-for-HEAD] [-h] [-v] [-d CVSROOT] [-A author-conv-file]
        [-p opts-for-cvsps] [-P file] [-C GIT_repository] [-z fuzz] [-i] [-k]
        [-u] [-s subst] [-a] [-m] [-M regex] [-S regex] [-L commitlimit]