nxagent manpage: add copysize option

Author: uli42

nx-X11/programs/Xserver/hw/nxagent/man/nxagent.1

@@ -570,6 +570,10 @@ enable using shared memory
 .B shpix=<bool>
 enable shared pixmaps support
 .TP 8
+.B copysize=<int>
+limit to the amount of data that can be pasted from an NX session into
+an external application. Default is unlimited.
+.TP 8
 .B client=<string>
 type of connecting operating system (supported: \fIlinux\fR,
 \fIwindows\fR, \fIsolaris\fR and \fImacosx\fR)