5794 Add reference to RFC 5903 to ike.config(4)

*** 1193,1197 ****
--- 1193,1201 ----
  Group. May 2003.
  .sp
  .LP
  Lepinksi, M. and Kent, S. \fIRFC 5114, Additional Diffie-Hellman Groups for Use
  with IETF Standards\fR. BBN Technologies, January 2008.
+ .sp
+ .LP
+ Fu, D. and Solinas, J. \fIRFC 5903, Elliptic Curve Groups modulo a Prime (ECP
+ Groups) for IKE and IKEv2\fR. NSA, June 2010.