update README

README.md

@@ -29,7 +29,7 @@ Gogs (Go Git Service) is a painless self-hosted Git service.
 
 - Due to testing purpose, data of [try.gogs.io](https://try.gogs.io) has been reset in **Jan 28, 2015** and will reset multiple times after. Please do **NOT** put your important data on the site.
 - The demo site [try.gogs.io](https://try.gogs.io) is running under `develop` branch.
-- <span style="color: red">You **MUST** read [CONTRIBUTING.md](CONTRIBUTING.md) before you start filing an issue or making a Pull Request, and **MUST** discuss with us on [Gitter](https://gitter.im/gogits/gogs) for UI changes and feature Pull Requests, otherwise it's high possibilities that we are not going to merge it.</span>
+- :exclamation::exclamation::exclamation:<span style="color: red">You **MUST** read [CONTRIBUTING.md](CONTRIBUTING.md) before you start filing an issue or making a Pull Request, and **MUST** discuss with us on [Gitter](https://gitter.im/gogits/gogs) for UI changes and feature Pull Requests, otherwise it's high possibilities that we are not going to merge it.</span>:exclamation::exclamation::exclamation:
 - If you think there are vulnerabilities in the project, please talk privately to **u@gogs.io**. Thanks!
 
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