README update

Author: drowsymike

README.md

@@ -1 +1,23 @@
-# rig
+# rig
+
+## Description
+Firmware for a password storage device based on STM32F401CC / STM32F411CC microcontrollers.  
+Written in C.
+
+## Target Hardware
+- MCU: STM32F401CC / STM32F411CC
+- Architecture: ARM Cortex-M4
+
+## Functionality
+- Secure storage of passwords
+- Access to stored data via device interface
+
+## Project Structure
+- `app/` — source files
+- `config/` — project config
+- `platform/` — startup-files, linker scripts etc.
+
+## Requirements
+- ARM GCC Toolchain
+- STM32 HAL / CMSIS
+- Make