Move the documentation tabs from top to left nav

[mamoodi]

• This change is worth documenting at https://docs.all-hands.dev/
• Include this change in the Release Notes. If checked, you must provide an end-user friendly description for your change below

End-user friendly description of the problem this fixes or functionality this introduces.

Move the documentation tabs from top to left nav

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Summarize what the PR does, explaining any non-trivial design decisions.

This makes it so the tabs at the top

are moved as regular items under the left nav bar

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Link of any specific issues this addresses:

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To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:4eae6b9-nikolaik   --name openhands-app-4eae6b9   docker.all-hands.dev/all-hands-ai/openhands:4eae6b9

[mamoodi]

Going to be doing the changes one by one.
@neubig and @xingyaoww.

Next up: Make the OH Cloud docs have a linear flow.