http2: Change in respondWithFile api not properly reflected in the docs

[akc42]

The respondWithFile api has changed between 8.4.0 and 8.5.0 with the addition of the onError option. This is important, because a simple response.stream.on('error'... no longer works after this change because the steam gets destroyed on an error (in particular on ENOENT) if onError doesn't exist so any attempt to resend a different file then crashes with stream undefined.

However the docs, although creating an onError function in the example then doesn't actually use it on the call to respondWithFile

[antoine-amara]

I can update http2 documentation, I found where I have to change the text. I will submit a PR soon with few updates.