Improve documentation arguments, mainly changing "thing: any"

[jasonwilliams]

Looking at https://tc39.es/proposal-temporal/docs/instant.html#from for example, i don't find the (thing: any) very helpful. I think we can do better here to help users understand what is being passed in. The example below shows only a string being used so why is thing's type not string? Well thats because you can also pass an Instant according to the type declaration.

So maybe we need to match the docs up with the type declarations more? like Temporal.Instant | string

[ptomato]

I guess the uncertainty here is due to the discrepancy between what the function technically accepts and what is recommended to pass. For example, you can pass a number (this actually works in Temporal.PlainDate.from(20210302)) or an object ({ valueOf() { return '2021-03-02T20:29Z'; }}) and they will get converted to strings. But, of course nobody should do this, so it's probably better to document the recommended usage.