Documentation: tweak description of log.date

The markup "'git log'\'s" produces a stray backslash in the
produced man page.  Removing the backslash fixes it.

While at it, tweak the surrounding description for readability.

Reported-by: Frédéric Brière <fbriere@fbriere.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -1296,10 +1296,11 @@ interactive.singlekey::
 	ignored if portable keystroke input is not available.
 
 log.date::
-	Set default date-time mode for the log command. Setting log.date
-	value is similar to using 'git log'\'s --date option. The value is one of the
-	following alternatives: {relative,local,default,iso,rfc,short}.
-	See linkgit:git-log[1].
+	Set the default date-time mode for the 'log' command.
+	Setting a value for log.date is similar to using 'git log''s
+	`\--date` option.  Possible values are `relative`, `local`,
+	`default`, `iso`, `rfc`, and `short`; see linkgit:git-log[1]
+	for details.
 
 log.decorate::
 	Print out the ref names of any commits that are shown by the log