docs: fix title format (#2594)

Author: iiio2

docs/1.guide/3.websocket.md

@@ -97,7 +97,7 @@ Now you can try it on `/websocket` route!
 > [!TIP]
 > Check out our [chat demo](https://nuxt-chat.pi0.io/) using Nitro Websocket API.
 
-## Server Sent Events (SSE)
+## Server-Sent Events (SSE)
 
 As an alternative to WebSockets, you can use [Server-sent events](https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events)