README: add project poster

Signed-off-by: Dhruva Gole <[email protected]>

Author: DhruvaG2000

README.md

@@ -1,5 +1,7 @@
 # GSoC 2022 Project
 
+![](https://dhruvag2000.github.io/Blog-GSoC22/assets/images/website_header.png)
+
 ## Arduino Core API module for zephyr
 
 To "complete" the core you need to copy or symlink the api folder from [this repo](https://github.com/arduino/ArduinoCore-API.git) to the target's ``cores/arduino`` folder.