Update license and contribution guide (#205)

Arto Kinnunen · web-flow · commit e45f8c7c684a · 2020-02-04T13:30:09.000+02:00
-Add CONTRIBUTING.md
-Update README.md to contain section about license and contribution
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -0,0 +1,5 @@
+# Contributing to Mbed OS
+
+Mbed OS is an open-source, device software platform for the Internet of Things. Contributions are an important part of the platform, and our goal is to make it as simple as possible to become a contributor.
+
+To encourage productive collaboration, as well as robust, consistent and maintainable code, we have a set of guidelines for [contributing to Mbed OS](https://os.mbed.com/docs/mbed-os/latest/contributing/index.html).
diff --git a/README.md b/README.md
@@ -383,3 +383,8 @@ In the PuTTY main screen, save the session, and click **Open**. This opens a con
 [INFO][brro]: 6LoWPAN Border Router Bootstrap Complete.
 ```
 
+## License and contributions
+
+The software is provided under Apache-2.0 license. Contributions to this project are accepted under the same license. Please see [contributing.md](CONTRIBUTING.md) for more info.
+
+This project contains code from other projects. The original license text is included in those source files. They must comply with our license guide.
