Update README.md

Add community paragraph

Author: emilmont

README.md

@@ -43,3 +43,11 @@ API Documentation
 * [DSP API](http://mbed.org/users/mbed_official/code/mbed-dsp/docs/tip/)
 * Flash File Systems: [SD](http://mbed.org/handbook/SDFileSystem), [USB MSD](http://mbed.org/handbook/USBHostMSD), [semihosted](http://mbed.org/handbook/LocalFileSystem)
 * [Peripheral Drivers API](http://mbed.org/handbook/Homepage)
+
+Community
+---------
+For discussing the development of the mbed SDK itself (Addition/support of microcontrollers/toolchains, build and test system, Hardware Abstraction Layer API, etc) please join our [mbed-devel mailing list](https://groups.google.com/forum/?fromgroups#!forum/mbed-devel).
+
+For every topic regarding the use of the mbed SDK, rather than its development, please post on the [mbed.org forum](http://mbed.org/forum/), or the [mbed.org Q&A](http://mbed.org/questions/).
+
+For reporting issues in the mbed libraries please open a ticket on the issue tracker of the relevant [mbed official library](http://mbed.org/users/mbed_official/code/).