Use Markdown for installer and manual docs #51

Job	Run time
Parse Commands	-1s
iOS (Xcode)	0s
WASM (Emscripten)	0s
macOS (Make)	0s
Windows (VS2022)	0s
Windows ${{ matrix.backend }}/${{ matrix.renderer }}	0s
macOS (Universal)	0s
macOS (Ninja)	0s
macOS ${{ matrix.backend }}/${{ matrix.renderer }}	0s
Windows (ARM64EC)	0s
macOS (Xcode)	0s
WAM (Emscripten)	0s
	-1s

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