Added main sections

Added sections to readme for requirements, instructions and how to test.

README.md

@@ -0,0 +1,18 @@
+# STM32 CMake+CppuTest Template
+
+## Requirements
+
+- An ARM compiler and linker.
+- Bash or a POSIX shell.
+- CMAKE version 3.20 or newer.
+- Cpputest 3.8 or newer.
+- Clangd LSP.
+- Git version control.
+
+## Instructions
+
+1. Clone/copy the repo locally.
+2. Check the requirements to make sure you're development enviroment is ready.
+3. Update the linker script files to target your current uC.
+
+## Running Tests