fix: use agreed path for closest peers endpoint

update endpoint path to /routing/v1/dht/closest/{peer-id}
as agreed in PR review comments

Author: lidel

src/routing/http-routing-v1.md

@@ -106,7 +106,7 @@ Each object in the `Providers` list is a record conforming to a schema, usually
 
 ## Peer Routing API
 
-### `GET /routing/v1/closest-peers/{peer-id}?[closerThan]&[count]`
+### `GET /routing/v1/dht/closest/{peer-id}?[closerThan]&[count]`
 
 #### Path Parameters