Update README.md

Author: deeppatel234

packages/devtool-module/README.md

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+## Package no longer supported. Please download directly from the [Chrome Web Store](https://chrome.google.com/webstore/detail/oddhnidmicpefilikhgeagedibnefkcf)
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+
 <p align="center">
   <img src="https://github.com/deeppatel234/react-context-devtool/blob/master/store-assets/cover.png?raw=true" width="80%"/>
 </p>