docs/cli: update martinvonz.github.io URLs to jj-vcs.github.io #17163

Job	Run time
Build jj-lib without Git support	46s
build (ubuntu-latest)	5m 13s
cargo-deny (advisories)	27s
build (macos-13)	8m 58s
Check protos	34s
cargo-deny (bans licenses sources)	30s
build (macos-14)	3m 55s
build (windows-latest)	10m 32s
Clippy check	2m 42s
Check that MkDocs can build the docs	10s
build (ubuntu-latest, --all-features)	6m 13s
Check that MkDocs can build the docs with latest Python and uv	20s
Check formatting	20s
	40m 40s

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