Add README to ComposeMail sample

Author: oscar-ad

demoProjects/ComposeMail/README.md

@@ -0,0 +1,29 @@
+## ComposeMail Sample
+Sample project that demonstrates the use of MotionLayout for a Mail client application.
+
+Includes an example of how to use MotionLayout with the paging library.
+## ComposeMail Overview
+-----------------------------
+
+### App Demo
+https://user-images.githubusercontent.com/61845568/176751838-834cdd38-e942-45b6-84a6-92e9d51adf0f.mp4
+
+### Mail Item - [Composable](https://github.com/androidx/constraintlayout/blob/229131491d82ff88cfe65bcaa0de436e9aeb4650/demoProjects/ComposeMail/app/src/main/java/com/example/composemail/ui/mails/MailItem.kt#L70)
+https://user-images.githubusercontent.com/61845568/176752054-d8791336-244e-4037-83f3-1d7204fd7562.mp4
+
+### New Mail Button - [Composable](https://github.com/androidx/constraintlayout/blob/229131491d82ff88cfe65bcaa0de436e9aeb4650/demoProjects/ComposeMail/app/src/main/java/com/example/composemail/ui/newmail/NewMail.kt#L321)
+https://user-images.githubusercontent.com/61845568/176752227-b79298ee-b4cb-4b2e-a39a-5baf73cc569a.mp4
+
+## Contributing
+
+If you'd like to get involved and contribute please read [CONTRIBUTING](https://github.com/androidx/constraintlayout/blob/main/CONTRIBUTING.md) for details on our code of conduct, and the process for submitting pull requests to us.
+
+## Authors
+
+- **Oscar Adame** ([oscar-ad](https://github.com/oscar-ad))
+
+See also the list of [contributors](https://github.com/androidx/constraintlayout/graphs/contributors) who participated in this project.
+
+## License
+
+This project is licensed under the Apache 2.0 License - see the [LICENSE](https://github.com/androidx/constraintlayout/blob/main/LICENSE) file for details