docs(nxdev): add tree lookup by path on documents

[bcabanes]

It adds the ability to setup arbitrary path (route) for any menu item in the documentation on nx.dev.

[nx-cloud-staging]

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✅ Successfully ran 12 targets

• nx affected --target=e2e --base=ff7a25a1ba42a94a863abe16b3a84359dd2c66a8 --head=024732fe0990747ee5eededd404222298ecd3585 --exclude=e2e-storybook,e2e-storybook-angular,e2e-react-native,e2e-detox --parallel=1
• nx affected --target=build --base=ff7a25a1ba42a94a863abe16b3a84359dd2c66a8 --head=024732fe0990747ee5eededd404222298ecd3585 --parallel=3
• nx affected --target=test --base=ff7a25a1ba42a94a863abe16b3a84359dd2c66a8 --head=024732fe0990747ee5eededd404222298ecd3585 --parallel=1
• nx affected --target=lint --base=ff7a25a1ba42a94a863abe16b3a84359dd2c66a8 --head=024732fe0990747ee5eededd404222298ecd3585 --parallel=3
• nx-cloud record -- yarn nx workspace-lint
• nx-cloud record -- yarn documentation
• nx build typedoc-theme
• nx-cloud record -- yarn depcheck
• nx-cloud record -- yarn check-lock-files
• nx-cloud record -- yarn check-commit
• nx-cloud record -- yarn nx format:check --base=ff7a25a1ba42a94a863abe16b3a84359dd2c66a8 --head=024732fe0990747ee5eededd404222298ecd3585
• nx-cloud record -- yarn check-imports

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Name	Status	Preview	Updated
nx-dev	✅ Ready (Inspect)	Visit Preview	Aug 10, 2022 at 5:29PM (UTC)

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