Document how to use with type systems TypeScript/ Flowtype

[gajus]

It is unclear how to define types for proxymissed promises.

Providing these guidelines would encourage broader pattern adoption.

[csuarez]

Related: https://github.com/kozhevnikov/proxymise/pull/8

[csuarez]

Now there is a @types/proxymise package to have correct typings:

import proxymise from 'proxymise';

function example(): ReturnType<typeof proxymise> {
       return proxymise(foo);
}