Updated Duration documentation

[stebogit]

Should you merge iamkun/dayjs#1099 😜

[iamkun]

I prefer not to add this to the docs. It's a little wired syntax I think. 🤔

[stebogit]

You mean the way I phrased it or the actual new option?

[iamkun]

I think we should not tell our new user that we could add a duration directly.

And adding this feature is only for migration from moment.js.

[stebogit]

But if it is not in the docs, how would people migrating from moment learn this is available?
Is there a "how to migrate from moment" document maybe?

[iamkun]

Cause moment support this, so we implement this. But this does not mean we should encourage our users to use this syntax.

I think a clear way for most users is to convert duration to milliseconds by our user and to added to the Dayjs instance.

[iamkun]

I'll close this since it's been a while since it's been opened. Feel free to reopen if you have updates on this