aiohttp instead of flask in example HTML

[jacopofar]

I tried the example chat application and was confused by the Flask reference. It's a refuse, this fixes it :)

[miguelgrinberg]

The title of the page should say python-socketio, as that is the name of this package. I missed updating it when I ported this from the Flask specific package.

Can I ask you to use this name, and also update the other examples in the same way? Thanks!

[jacopofar]

OK, did it!