Clarify in voicemail.conf that certain variables are in seconds

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@2460 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configs/voicemail.conf.sample

@@ -10,11 +10,11 @@ serveremail=asterisk
 ;serveremail=asterisk@linux-support.net
 ; Should the email contain the voicemail as an attachment
 attach=yes
-; Maximum length of a voicemail message
+; Maximum length of a voicemail message in seconds
 ;maxmessage=180
-; Minimum length of a voicemail message
+; Minimum length of a voicemail message in seconds
 ;minmessage=3
-; Maximum length of greetings
+; Maximum length of greetings in seconds
 ;maxgreet=60
 ; How many miliseconds to skip forward/back when rew/ff in message playback
 skipms=3000