readme: replace github badge by rtd

Author: ederjc

README.md

@@ -1,7 +1,7 @@
 # Arduino Core for Infineon's XMC™ Microcontrollers
 
-![compile examples badge](https://github.com/Infineon/XMC-for-Arduino/actions/workflows/compile-platform-examples.yml/badge.svg)
-![build docs badge](https://github.com/Infineon/XMC-for-Arduino/actions/workflows/docs.yml/badge.svg)
+![Compilation Status](https://github.com/Infineon/XMC-for-Arduino/actions/workflows/compile-platform-examples.yml/badge.svg)
+[![Documentation Status](https://readthedocs.org/projects/xmc-arduino/badge/?version=latest)](https://xmc-arduino.readthedocs.io/en/latest/?badge=latest)
 
 This project integrates Infineon's 32-bit XMC™ Industrial Arm® Cortex®-M Microcontroller into the [Arduino](https://www.arduino.cc/en/Guide/Introduction) ecosystem.
 
@@ -46,4 +46,4 @@ We welcome community contributions! Please refer to our [contribution guidelines
 
 ## License
 
-See the [LICENSE](LICENSE.md) file for more details about the license.
+See the [LICENSE](LICENSE.md) file for more details about the license.