Add related content section to SocketAddress.md

Link to related architecture.

Author: Amanda Butler

docs/reference/api/connectivity/networksocket/SocketAddress.md

@@ -11,3 +11,7 @@ Use the SocketAddress class to represent the IP address and port pair of a uniqu
 Here is an example to read current UTC time. This example uses the SocketAddress class to get the server IP address and port.
 
 [![View code](https://www.mbed.com/embed/?url=https://os.mbed.com/teams/mbed_example/code/mbed-os-example-udp-sockets/)](https://os.mbed.com/teams/mbed_example/code/mbed-os-example-udp-sockets/file/cf516d904427/main.cpp)
+
+### Related content
+
+- [IP networking architecture](ip-networking.html).