Update documentation to reflect async functions in 4.0

[JaneJeon]

Honestly 90% of the examples in the README are synchronous and I literally can't tell whether a method is async or not (e.g. I was surprised when extendRole was failing, and turns out it was async for some reason) because of it.

It would be nice to just say "hey all these functions are synchronous on <4.0" at the top of the documentation and update the examples of async methods to reflect that. It's just confusing because some are async, some are not, and I can't tell by reading the README!

P.S. to make it easier for people to migrate between versions, please maintain a changelog by using something like https://github.com/sindresorhus/np for every version you release.

[koladilip]

@agnelnanda please update the documentation

[koladilip]

Can you check if the documentation is ok now?

[JaneJeon]

@koladilip I think it's just best to remove all of the synchronous examples from the README, it's confusing and if anyone is using versions <4.0, they'll be reading off the README of the previous commits.

(P.S. please consider using np for releases, I have no idea what changed since 4.0)

[agnelNandapurapu]

Done.