I haven't tried to build the package but I think something like this patch should put a description of the '-s' option in the man page.
--- wpa_supplicant.8.old 2010-12-27 14:11:58.000000000 -0500 +++ wpa_supplicant.8 2010-12-27 14:13:43.000000000 -0500 @@ -296,6 +296,9 @@ \fB-K\fR Include keys (passwords, etc.) in debug output. .TP +\fB-s\fR +log output to syslog instead of stdout. +.TP \fB-t\fR Include timestamp in debug messages. .TP
