Update Test kernel readme

Build/Test Kernel/readme.md → Build/Test Kernel/README.md

@@ -1,10 +1,16 @@
-remove the .iso file, and run the commands in the iso root dir:
+# Build test kernel
+Remove the .iso file, and run the commands in the iso root dir:
 
-compiling  output.bin :
+Compiling  output.bin :
 
+```cmd
 nasm -f bin -o output.bin kernel.asm 
+```
 
-build iso:
+Build iso:
+
+```cmd 
 mkisofs -R -b isolinux.bin -no-emul-boot -boot-load-size 4 -boot-info-table -o boot.iso
+```
 
 then use boot.iso as boot image.