Docs: turn getopt examples into doctests #102

Job	Run time
Interpreter (Debug)	6m 56s
Free-Threaded (Debug) (19)	10m 14s
i686-pc-windows-msvc/msvc (Debug)	17m 45s
i686-pc-windows-msvc/msvc (Release)	22m 36s
x86_64-pc-windows-msvc/msvc (Debug)	18m 23s
x86_64-pc-windows-msvc/msvc (Release)	21m 11s
aarch64-pc-windows-msvc/msvc (Debug)	5m 3s
aarch64-pc-windows-msvc/msvc (Release)	6m 1s
x86_64-apple-darwin/clang (Debug)	17m 48s
x86_64-apple-darwin/clang (Release)	20m 51s
aarch64-apple-darwin/clang (Debug)	2m 51s
aarch64-apple-darwin/clang (Release)	2m 37s
x86_64-unknown-linux-gnu/gcc (Debug)	7m 41s
x86_64-unknown-linux-gnu/gcc (Release)	17m 57s
x86_64-unknown-linux-gnu/clang (Debug)	7m 50s
x86_64-unknown-linux-gnu/clang (Release)	13m 5s
aarch64-unknown-linux-gnu/gcc (Debug)	1h 13m 7s
aarch64-unknown-linux-gnu/gcc (Release)	36m 2s
aarch64-unknown-linux-gnu/clang (Debug)	1h 7m 23s
aarch64-unknown-linux-gnu/clang (Release)	37m 50s
	6h 53m 11s

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