[LYN-4366] Add API documentation for AzNetworking, Mutiplayer Gem, and Multiplayer Compression Gem classes.

Signed-off-by: stramer <stramer@amazon.com>

Code/Framework/AzNetworking/AzNetworking/ConnectionLayer/IConnection.h

@@ -44,6 +44,12 @@ namespace AzNetworking
 
     //! @class IConnection
     //! @brief interface class for network connections.
+    //!
+    //! IConnection provides a pure-virtual interface for all network connection types.  The two child classes are TcpConnection
+    //! and UdpConnection, though the pure-virtual interface operates largely the same for both. IConnections provide access to
+    //! a ConnectionMetrics object which provides a variety of metrics on the connection itself such as data rate, RTT and
+    //! packet statistics. 
+
     class IConnection
     {
     public:

Code/Framework/AzNetworking/AzNetworking/ConnectionLayer/IConnectionListener.h

@@ -22,6 +22,12 @@ namespace AzNetworking
 {
     //! @class IConnectionListener
     //! @brief interface class for application layer dealing with connection level events.
+    //!
+    //! IConnectionListener defines an abstract interface that the user of AzNetworking is expected to implement to react and
+    //! handle all IConnection related events, including the handling of any received IPacket derived packets.  The AzNetworking
+    //! user should derive a handler class from IConnectionListener, and provide an instance of that handler to any
+    //! INetworkInterface the user instantiates.  The lifetime of the IConnectionListener must outlive the lifetime of the
+    //! INetworkInterface.
     class IConnectionListener
     {
     public:

Code/Framework/AzNetworking/AzNetworking/ConnectionLayer/IConnectionSet.h

@@ -18,6 +18,11 @@ namespace AzNetworking
 {
     //! @class IConnectionSet
     //! @brief interface class for managing a set of connections.
+    //!
+    //! IConnectionSet defines a simple interface for working with an abstract set of IConnections bound to an
+    //! INetworkInterface.  Generally users of AzNetworking will not have reason to interact directly with the IConnectionSet,
+    //! as its interface is completely wrapped by INetworkInterface.
+
     class IConnectionSet
     {
     public: