Docs imply the only way to use i3ipc is with asyncio

[davemq]

docs/index.rst implies that the only way to use i3ipc is with asyncio. But the example in README.rst shows this is not the case. Those reading the reference documentation will need to already know how to use asyncio or learn enough about it to even try the the reference documentation examples. E.g. there's no example of using asyncio.run() to run the code, and typing the code in the REPL gets errors about not being in a function.