Update C Guidelines

[danieljurek]

CI currently builds for the following OS/arch/compiler configurations:

Operating System	Architecture	Compiler Version
Ubuntu 22.04	ARM	arm-none-eabi-gcc 10.3.1
Ubuntu 22.04	x64	gcc 11.4.0
Windows 2019	x64	MSVC 14.29
Windows 2022	x86	MSVC 14.43
Windows 2022	x64	MSVC 14.43
macOS	x64	Xcode 15.4 AppleClang 15.0.0

Existing table: https://azure.github.io/azure-sdk/clang_design.html#supported-platforms