change "<id>" to "<subscription_id>" in NIP-01

fixes #66

nips/01.md

@@ -52,8 +52,8 @@ Relays expose a websocket endpoint to which clients can connect.
 Clients can send 3 types of messages, which must be JSON arrays, according to the following patterns:
 
   * `["EVENT", <event JSON as defined above>`], used to publish events.
-  * `["REQ", <id>, <filter JSON>...`], used to request events and subscribe to new updates.
-  * `["CLOSE", <id>]`, used to stop previous subscriptions.
+  * `["REQ", <subscription_id>, <filter JSON>...`], used to request events and subscribe to new updates.
+  * `["CLOSE", <subscription_id>]`, used to stop previous subscriptions.
 
 `<id>` is a random string that should be used to represent a subscription. The same