Fix the ech_accept comment.

This was fixed in review, but we forgot to update the comment.

Change-Id: If1fdd9211ff085edeb50457edf0caba5e31b6d16
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/47448
Reviewed-by: Dan McArdle <dmcardle@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

ssl/internal.h

@@ -1859,8 +1859,8 @@ struct SSL_HANDSHAKE {
   // influence the handshake on match.
   UniquePtr<SSL_HANDSHAKE_HINTS> hints;
 
-  // ech_accept, on the server, indicates whether the server should overwrite
-  // part of ServerHello.random with the ECH accept_confirmation value.
+  // ech_accept, on the server, indicates whether the server negotiated ECH and
+  // is handshaking with the inner ClientHello.
   bool ech_accept : 1;
 
   // ech_present, on the server, indicates whether the ClientHello contained an