"Which Temporal type do I use" flowchart

[ptomato]

Originally from tc39/proposal-temporal#655

It would be useful to have a "Which Temporal type do I use" flowchart in the documentation, similar to "Which STL container do I use"

See also

• https://github.com/Reactive-Extensions/RxJS/blob/master/doc/gettingstarted/which-static.md
• https://github.com/Reactive-Extensions/RxJS/blob/master/doc/gettingstarted/which-instance.md