message: Add beta phase warning to README
diff: -# bold
  +# Bold
  [![Build Status](https://travis-ci.org/laboratoriobridge/bold.svg?branch=master)](https://travis-ci.org/laboratoriobridge/bold)
  [![codecov](https://codecov.io/gh/laboratoriobridge/bold/branch/master/graph/badge.svg)](https://codecov.io/gh/laboratoriobridge/bold)
  @@ -7,6 +7,12 @@ https://bold.bridge.ufsc.br/
  React implementation of the **Bold Design System**.
  +## WARNING: Beta phase
  +
  +This project is currently in beta phase and its API may change without following semver.
  +
  +The first stable release (probably `1.0.0`) will follow [semver](https://semver.org/).
  +
  ## Getting started
  ```sh
  