Documentation fix - waitfordialtone is not boolean, it's time in milliseconds

Changing text in chan_dahdi.conf sample to be accurate.

(issue ASTERISK-22308)
(closes issue ASTERISK-22308)
Reported By: Malcolm Davenport
........

Merged revisions 398880 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@398881 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configs/chan_dahdi.conf.sample

@@ -582,7 +582,8 @@ usecallerid=yes
 ; easily be re-attaching to a prior incoming call that was not yet hung up).
 ; This option changes the hangup to wait for a dialtone on the line, before
 ; marking the line as once again available for use with outgoing calls.
-;waitfordialtone=yes
+; Specified in milliseconds, not set by default.
+;waitfordialtone=1000
 ;
 ; For analog lines, enables Asterisk to use dialtone detection per channel
 ; if an incoming call was hung up before it was answered.  If dialtone is