distinguish between seeds and manual peers in the config/flags

- we only use seeds if we can’t connect to peers in the addrbook.
- we always connect to nodes given in config/flags

Refs #864

rpc/core/doc.go

@@ -94,7 +94,7 @@ Endpoints that require arguments:
 /broadcast_tx_commit?tx=_
 /broadcast_tx_sync?tx=_
 /commit?height=_
-/dial_seeds?seeds=_
+/dial_manual_peers?manual_peers=_
 /subscribe?event=_
 /tx?hash=_&prove=_
 /unsafe_start_cpu_profiler?filename=_