learn: update usage statement

Use <foo|bar> since that seems to be the favored notation
for required command args (taking a hint from git(1) manpage).
While we're at it, remove the space after '<' for the redirect
to match git.git coding style.

diff --git a/script/public-inbox-learn b/script/public-inbox-learn
index d2d665d580b5f4803d2afd66fd45b333b4c1a99b..ad1329859ce253304507046547667ad21c45464e 100755 (executable)
--- a/script/public-inbox-learn
+++ b/script/public-inbox-learn
@@ -4,7 +4,7 @@
 #
 # Used for training spam (via SpamAssassin) and removing messages from a
 # public-inbox
-my $usage = "$0 (spam|ham) < /path/to/message";
+my $usage = "$0 <spam|ham|rm> </path/to/message";
 use strict;
 use warnings;
 use PublicInbox::Config;
@@ -39,7 +39,7 @@ my $mime = PublicInbox::MIME->new(eval {
        $data
 });
 
-# spam is removed from all known inboxes
+# spam is removed from all known inboxes since it is often Bcc:-ed
 if ($train eq 'spam') {
        $pi_config->each_inbox(sub {
                my ($ibx) = @_;