updated readme

README.md

@@ -1,2 +1,11 @@
 # calculator
 An OS for an STM32-based calculator  
+  
+Trying to make an operating system for a calculator based on the STM32L476RG, using its associated Nucleo board. Starting from scratch because it's fun.  
+  
+Required packages:
+* arm-none-eabi toolchain
+* openocd
+* make
+  
+Use run.sh to upload the final output to the processor.