[DCCP]: Update documentation

As Eddie Kohler points out the RFC is Proposed Standard not experimental.
Also removed documentation about deprecated socket option.

Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

Documentation/networking/dccp.txt

@@ -19,7 +19,8 @@ for real time and multimedia traffic.
 
 It has a base protocol and pluggable congestion control IDs (CCIDs).
 
-It is at experimental RFC status and the homepage for DCCP as a protocol is at:
+It is at proposed standard RFC status and the homepage for DCCP as a protocol
+is at:
 	http://www.read.cs.ucla.edu/dccp/
 
 Missing features
@@ -34,9 +35,6 @@ The known bugs are at:
 Socket options
 ==============
 
-DCCP_SOCKOPT_PACKET_SIZE is used for CCID3 to set default packet size for
-calculations.
-
 DCCP_SOCKOPT_SERVICE sets the service. The specification mandates use of
 service codes (RFC 4340, sec. 8.1.2); if this socket option is not set,
 the socket will fall back to 0 (which means that no meaningful service code