Update WebSocket subscription limits (#890)

Author: Onewaysidewalks

fern/api-reference/websockets/subscription-api.mdx

@@ -86,7 +86,7 @@ Next, install a command line tool for making WebSocket requests such as [wscat](
 The following limits apply for WebSocket connections:
 
 * There is a limit of **100 WebSocket connections** for the FREE tier and **2,000 WebSocket connections** for all other tiers, with a maximum of 50,000 connections per instance.
-* **No limits** on the number of **parallel** WebSocket subscriptions per WebSocket connection.
+* There is a limit of **1,000 unique subscriptions** per WebSocket connection.
 * The maximum size of a JSON-RPC `batch` request that can be sent over a WebSocket connection is 1000
 
 ***