ACTION-25: Add text about internal timeout

Reflecting on this, I think we don't need to add any text. The PositionOptions::timeout attribute is defined well enough. The "internal timeout", on the other hand, is something that an implementation must decide for itself. It can either rely on the built-in timeouts of the various low level APIs that it uses to get location (e.g. GPS, HTTP) or set a reasonable internal timeout of its own. Either way, the result of such an internal timeout is always POSITION_UNAVAILABLE and the decision on if and how to pick the internal timeout is an implementation detail.

I therefore do not think the spec needs changing.