quic: fix doc opened instead of open

Author: martenrichter

doc/api/quic.md

@@ -1921,7 +1921,7 @@ Either `'application'` or `'transport'`. Indicates the namespace of
 added: v23.8.0
 -->
 
-### `stream.open`
+### `stream.opened`
 
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 added: REPLACEME