refactor: rename 'Topology' to 'Routes'

Since that is what it is. By contrast, when the docs talk about
topology they actually refer to the peer connectivity graph.

docs/architecture.txt

@@ -1,5 +1,5 @@
 Router:
-  - Starts Topology
+  - Starts Routes
   - Starts Connection Maker
   - Starts TCP Listener
   - Starts UDP Listener
@@ -17,9 +17,9 @@ Router:
   frames and forwards them to a local peer (or peers) (router.Sniff /
   router.handleCapturedPacket)
 
-- Topology
+- Routes
   Maintains unicast and broadcast routing tables which can be read
-  directly from any thread by just obtaining a readlock on topology.
+  directly from any thread by just obtaining a read lock on Routes.
   - Unicast answers the question "If I want to send a packet to peer
     X, which of the peers I'm connected to should I send the packet
     to?"
@@ -27,7 +27,7 @@ Router:
     the time it reaches me, which of my connected peers is X expecting
     me to pass the packet to?"
   Also spawns a thread which runs an actor loop, responding to
-  requests to encode all peers, or rebuild the routing tables.
+  requests to rebuild the routing tables.
 
 - Connection Maker
   Spawns a thread which runs an actor loop. This actor loop is passed
@@ -55,7 +55,7 @@ Router:
   router udp listener processes to send traffic to neighbouring
   peers. This is done directly with read locks. In these methods, we
   inspect the unicast and broadcast routing tables as generated by
-  Topology.
+  Routes.
 
 - Connections
   The connection life cycle is as follows: