Confusion around when to use timeout vs recv_timeout

Getting ` {:error, %HTTPoison.Error{id: nil, reason: :timeout}}` in about 6 seconds with my options set as `[timeout: 30_000]`. After much digging and confusion, it seems that the timeout is stemming from `recv_timeout` being too low. I found this confusing for 2 reasons:
1) `reason: :timeout` is reported, which suggests that the `timeout` is the appropriate option to adjust.
2) The docs around `timeout` vs `recv_timeout` are pretty vague... I'm still not sure exactly what each one does and how they are different.

Start by reviewing the documentation for the timeout and recv_timeout options and the error output showing reason: :timeout. Clarify how the two options differ and which behavior each controls, then verify that the documented explanation matches the reported six-second timeout scenario.

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