Added README instruction about KFLAGS

Author: chrisdedman

README.md

@@ -34,6 +34,11 @@ Make sure you have an ARM cross-compiler installed (e.g., `arm-none-eabi-gcc`) a
 make
 ```
 
+Developers also have the option to run the kernel with custom flags such as:
+```sh
+make KFLAGS="-USE_KTESTS -MY_DEFFLAG"
+```
+
 > [!IMPORTANT]
 > 
 > `make` will clean, build, and run the kernel in QEMU. You can also run 
@@ -64,4 +69,4 @@ For more details about this kernel, refer to the [AstraKernel Documentation](htt
 
 ## License
 
-This project is licensed under the GNU GENERAL PUBLIC License. See the [LICENSE](LICENSE) file for details.
+This project is licensed under the GNU GENERAL PUBLIC License. See the [LICENSE](LICENSE) file for details.