update readme

Author: cuu

Code/pico_multi_booter/README.md

@@ -8,6 +8,8 @@ Here is a bootloader for PicoCalc combined slightly modified [PicoMite](https://
 
 ## How to compile
 ```
+git clone --recursive https://github.com/clockworkpi/PicoCalc.git
+cd PicoCalc/Code/pico_multi_booter
 export PICO_SDK_PATH=/where/picosdk/is
 mkdir build
 cd build

Code/picocalc_helloworld/README.md

@@ -4,6 +4,9 @@ Demonstrate how to use spi screen, i2c keyboard and psram on PicoCalc.
 
 ## Building
 ```
+git clone --recursive https://github.com/clockworkpi/PicoCalc.git
+cd PicoCalc/Code/picocalc_helloworld/
+
 mkdir build
 cd build
 export PICO_SDK_PATH=/where/pico-sdk/is