Add Known Issues section to CHANGELOG (#68)

CHANGELOG.md

@@ -7,3 +7,9 @@
 * Remove requirement of `sudo` for `iotedgehubdev start` and `iotedgehubdev modulecred` command
 * Rename EdgeHub runtime to IoT Edge simulator
 * Fix a issue which causes duplicate D2C messages
+
+### Known Issues
+* [#67](https://github.com/Azure/iotedgehubdev/issues/67) Running Python and C modules which relies on SDK's support is not ready yet 
+* [#62](https://github.com/Azure/iotedgehubdev/issues/62) Debugging C# modules may fail with Windows container due to incorrect timestamp
+* [#30](https://github.com/Azure/iotedgehubdev/issues/30) Debugging C# modules locally on macOS requires manually adding edge-device-ca.cert.pem to Keychain, and removing the EdgeModuleCACertificateFile environment variable
+* [#5](https://github.com/Azure/iotedgehubdev/issues/5) Python 3.7 is not supported yet because Python Docker SDK does not support Python 3.7