http2: correcting the heading format

PR-URL: #22262
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: George Adams <george.adams@uk.ibm.com>

doc/api/http2.md

@@ -113,7 +113,7 @@ User code will not create `Http2Session` instances directly. Server-side
 new HTTP/2 connection is received. Client-side `Http2Session` instances are
 created using the `http2.connect()` method.
 
-#### `Http2Session` and Sockets
+#### Http2Session and Sockets
 
 Every `Http2Session` instance is associated with exactly one [`net.Socket`][] or
 [`tls.TLSSocket`][] when it is created. When either the `Socket` or the