Fix up std.syslog example

Thanks to InvertedAcceleration <chris.magee@velocity42.com> for a
patch that pointed me at documentation that needed improving.

doc/sphinx/reference/vmod_std.rst

@@ -95,9 +95,10 @@ Prototype
 Return value
 	Void
 Description
-	Logs *string* to syslog marked with *priority*.
+	Logs *string* to syslog marked with *priority*.  See your
+	system's syslog.h file for the legal values of *priority*.
 Example
-	std.syslog( LOG_USER|LOG_ALERT, "There is serious troble");
+	std.syslog(8 + 1, "Something is wrong");
 
 fileread
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