Document helpers needed per target platform

[tuukkamustonen]

So, apparently we need these helpers (quite like polyfills) to target platforms, which don't have some of the newer features yet (like async/await). Ok.

However, if I target es2017, es2018 (or es2025 when it comes), tsc will produce code that doesn't need to rely on these helpers, and there's no need for this lib?

Would it make sense to document which helpers are required on which target, so I can judge if I need this library at all?

(Why external library? Why not just bundle this functionality into typescript, which already seems to have a copy of these helpers anyway - tslib is needed only to import the helpers instead of multiplying them now?)