doc: update reduce-memory.md peer connections info

doc/reduce-memory.md

@@ -24,9 +24,13 @@ The size of some in-memory caches can be reduced. As caches trade off memory usa
 
 ## Number of peers
 
-- `-maxconnections=<n>` - the maximum number of connections, this defaults to 125. Each active connection takes up some
+- `-maxconnections=<n>` - the maximum number of connections, which defaults to 125. Each active connection takes up some
-  memory. This option applies only if incoming connections are enabled, otherwise the number of connections will never
+  memory. This option applies only if inbound connections are enabled; otherwise, the number of connections will not
-  be more than 10. Of the 10 outbound peers, there can be 8 full-relay connections and 2 block-relay-only ones.
+  be more than 11. Of the 11 outbound peers, there can be 8 full-relay connections, 2 block-relay-only ones,
+  and occasionally 1 short-lived feeler or extra outbound block-relay-only connection.
+
+- These limits do not apply to connections added manually with the `-addnode` configuration option or
+  the `addnode` RPC, which have a separate limit of 8 connections.
 
 ## Thread configuration