message: Include prerelease install channel in README.md
diff: Accessible, customizable, delightful date & time pickers for [@material-ui/core](https://material-ui.com/)
  -You can find a pre-release (next) docs version [here](https://next.material-ui-pickers.dev/)
  -
  [![npm package](https://img.shields.io/npm/v/material-ui-pickers.svg)](https://www.npmjs.org/package/material-ui-pickers)
  [![npm download](https://img.shields.io/npm/dm/material-ui-pickers.svg)](https://www.npmjs.org/package/material-ui-pickers)
  [![codecov](https://codecov.io/gh/dmtrKovalenko/material-ui-pickers/branch/develop/graph/badge.svg)](https://codecov.io/gh/dmtrKovalenko/material-ui-pickers)
  @@ -22,15 +20,26 @@ You can find a pre-release (next) docs version [here](https://next.material-ui-p
  ### Installation
  -Available as npm package.
  +Stable channel (v2). [Docs site](https://material-ui-pickers.dev/).
  ```sh
  +// via npm
  npm i material-ui-pickers
  -// or via yarn
  +// via yarn
  yarn add material-ui-pickers
  ```
  +Next channel (v3-alpha). [Docs site](https://next.material-ui-pickers.dev/).
  +
  +```sh
  +// via npm
  +npm i material-ui-pickers@next
  +
  +// via yarn
  +yarn add material-ui-pickers@next
  +```
  +
  Now choose the library that pickers will use to work with date. We are providing interfaces for [moment](https://momentjs.com/), [luxon](https://moment.github.io/luxon/), [dayjs](https://github.com/iamkun/dayjs) and [date-fns v2](https://date-fns.org/). If you are not using moment in the project (or dont have it in the bundle already) we suggest using date-fns or luxon, because they are much lighter and will be correctly tree-shaked from the bundle. Note, that we are fully relying on [date-io](https://github.com/dmtrKovalenko/date-io) for supporting different libraries.
  ```sh
  