Add `mdbook` and refactor `README.md` #359

Job	Run time
lint	12s
yara (ubuntu-22.04) / yara	9s
yara (ubuntu-22.04) / output	4s
docs-build	23s
yara-output	3s
clippy	21s
test (ubuntu-22.04, x86_64-unknown-linux-gnu)	29s
docs-deploy	0s
	1m 41s

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