docs: add "The Duroxide family" cross-link section to README #30

Job	Run time
windows (x86_64-pc-windows-msvc)	7m 26s
macos (aarch64-apple-darwin)	3m 1s
linux (ubuntu-latest, x86_64-unknown-linux-gnu)	5m 24s
macos (x86_64-apple-darwin)	3m 18s
sdist	15s
linux (ubuntu-24.04-arm, aarch64-unknown-linux-gnu)	5m 6s
Smoke (local) windows-latest py3.12	39s
Publish to PyPI	0s
Smoke (registry) ${{ matrix.os }} py${{ matrix.python }}	0s
Report registry smoke failure	0s
	25m 9s

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