README: add beta information

Author: mortend

README.md

@@ -4,6 +4,7 @@
 <p align="center">
 <a href="https://ci.appveyor.com/project/mortend/fuse-sdk/branch/master"><img src="https://img.shields.io/appveyor/ci/mortend/fuse-sdk/master.svg?logo=appveyor&amp;logoColor=silver&amp;style=flat-square" alt="AppVeyor build status"></a>
 <a href="https://www.npmjs.com/package/fuse-sdk"><img src="https://img.shields.io/npm/v/fuse-sdk.svg?style=flat-square" alt="NPM package"></a>
+<a href="https://www.npmjs.com/package/fuse-sdk"><img src="https://img.shields.io/npm/v/fuse-sdk/beta.svg?style=flat-square" alt="NPM beta"></a>
 <a href="https://fusecommunity.slack.com/"><img src="https://img.shields.io/badge/chat-on slack-blue.svg?style=flat-square" alt="Slack"></a>
 <a href="https://opencollective.com/fuse-open"><img src="https://opencollective.com/fuse-open/all/badge.svg?label=financial+contributors&amp;style=flat-square" alt="Financial Contributors on Open Collective"></a>
 <a href="LICENSE.txt"><img src="https://img.shields.io/github/license/fuse-open/fuse-sdk.svg?style=flat-square" alt="License: MIT"></a>
@@ -43,6 +44,10 @@ npm install fuse-sdk
 
 This will install Fuse SDK, including [`uno`](https://github.com/fuse-open/uno) and [a set of libraries](https://github.com/fuse-open/fuselibs) used to build [Fuse](https://fuseopen.com) apps.
 
+### Beta releases
+
+We are currently working on [`beta-3.0`](https://github.com/fuse-open/fuse-sdk/tree/beta-3.0). Releases made from this branch are tagged `@beta` on NPM.
+
 ## Usage
 
 Please refer to the following links for information about using Fuse SDK.