install_update_dovecot.sh: name default spam filter as 'Move Spam'.

install_update_dovecot.sh

@@ -2016,6 +2016,7 @@ mkdir -p /usr/local/dovecot-${_version}/etc/dovecot/sieve/global/
 echononl "\tCeate global sieve script"
 cat <<EOF > /usr/local/dovecot-${_version}/etc/dovecot/sieve/move-spam.sieve
 require ["fileinto"];
+# rule:[Move Spam]
 # Move spam to spam folder
 if header :contains "X-Spam-Flag" ["YES"] {
   fileinto "$spam_folder";