Clarify URI syntax for connecting to ray cluster

[kevinjqliu]

Describe the bug
Ray exposes two ports, 6379 and 10001, depending on which port is used, the syntax for daft.context.set_runner_ray is different.

For example:
Both of these works

daft.context.set_runner_ray(address="127.0.0.1:6379")
daft.context.set_runner_ray(address="ray://127.0.0.1:10001")

But this does not

daft.context.set_runner_ray(address="ray://127.0.0.1:6379")

This might be a Ray thing, but I think it'll make sense to clarify it in the Daft docs. Esp, since there are lots of examples using the ray:// prefix https://github.com/search?q=repo%3AEventual-Inc%2FDaft+%22ray%3A%2F%2F%22&type=code

To Reproduce
Code above

Expected behavior
As a user, I would want Ray to work regardless of which "style" I specify.

daft.context.set_runner_ray(address="127.0.0.1:6379")
daft.context.set_runner_ray(address="127.0.0.1:10001")
daft.context.set_runner_ray(address="ray://127.0.0.1:6379")
daft.context.set_runner_ray(address="ray://127.0.0.1:10001")

Screenshots
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Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.

[samster25]

assigning @raunakab!