cgitrc: explain new local-time option

Signed-off-by: Stefan Naewe <stefan.naewe@atlas-elektronik.com>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgitrc

@@ -44,6 +44,8 @@
 ## print all tags.
 #summary-tags=0
 
+## Enable/disable display of localtime vs. GMT. Set to 1 for localtime.
+#local-time=0
 
 ## The "Idle" column on the repository index page can read a timestamp
 ## from the specified agefile (if this file cannot be found, the mtime