Update link to LibVNCServer in man page

Author: bk138

x11vnc.1

@@ -6963,6 +6963,6 @@ run by \fB-accept\fR, \fB-gone\fR and other cases:
 .IR https://github.com/LibVNC/x11vnc
 .SH AUTHORS
 x11vnc was written by Karl J. Runge <runge@karlrunge.com>,
-it is part of the LibVNCServer project <http://sf.net/projects/libvncserver>.
+it is part of the LibVNCServer project <https://github.com/LibVNC/libvncserver>.
 This manual page is based one the one written by Ludovic Drolez
 <ldrolez@debian.org>, for the Debian project (both may be used by others).