[doc] Describe connection types in more depth.

src/net.h

@@ -118,12 +118,54 @@ struct CSerializedNetMsg
  * information we have available at the time of opening or accepting the
  * connection. Aside from INBOUND, all types are initiated by us. */
 enum class ConnectionType {
-    INBOUND, /**< peer initiated connections */
-    OUTBOUND_FULL_RELAY, /**< full relay connections (blocks, addrs, txns) made automatically. Addresses selected from AddrMan. */
-    MANUAL, /**< connections to addresses added via addnode or the connect command line argument */
-    FEELER, /**< short lived connections used to test address validity */
-    BLOCK_RELAY, /**< only relay blocks to these automatic outbound connections. Addresses selected from AddrMan. */
-    ADDR_FETCH, /**< short lived connections used to solicit addrs when starting the node without a populated AddrMan */
+    /**
+     * Inbound connections are those initiated by a peer. This is the only
+     * property we know at the time of connection, until P2P messages are
+     * exchanged.
+     */
+    INBOUND,
+
+    /**
+     * These are the default connections that we use to connect with the
+     * network. There is no restriction on what is relayed- by default we relay
+     * blocks, addresses & transactions. We automatically attempt to open
+     * MAX_OUTBOUND_FULL_RELAY_CONNECTIONS using addresses from our AddrMan.
+     */
+    OUTBOUND_FULL_RELAY,
+
+
+    /**
+     * We open manual connections to addresses that users explicitly inputted
+     * via the addnode RPC, or the -connect command line argument. Even if a
+     * manual connection is misbehaving, we do not automatically disconnect or
+     * add it to our discouragement filter.
+     */
+    MANUAL,
+
+    /**
+     * Feeler connections are short lived connections used to increase the
+     * number of connectable addresses in our AddrMan. Approximately every
+     * FEELER_INTERVAL, we attempt to connect to a random address from the new
+     * table. If successful, we add it to the tried table.
+     */
+    FEELER,
+
+    /**
+     * We use block-relay-only connections to help prevent against partition
+     * attacks. By not relaying transactions or addresses, these connections
+     * are harder to detect by a third party, thus helping obfuscate the
+     * network topology. We automatically attempt to open
+     * MAX_BLOCK_RELAY_ONLY_CONNECTIONS using addresses from our AddrMan.
+     */
+    BLOCK_RELAY,
+
+    /**
+     * AddrFetch connections are short lived connections used to solicit
+     * addresses from peers. These are initiated to addresses submitted via the
+     * -seednode command line argument, or under certain conditions when the
+     * AddrMan is empty.
+     */
+    ADDR_FETCH,
 };
 
 class NetEventsInterface;