Update docker image guide

[melissawm]

Description

This PR moves the "Build and Upload MaxText Docker Images" guide to the tutorials section and removes redundant installation instructions to rely on the main installation page.

Tests

Documentation build correctly locally.

Checklist

Before submitting this PR, please make sure (put X in square brackets):

• [N/A] I have performed a self-review of my code. For an optional AI review, add the gemini-review label.
• [N/A] I have necessary comments in my code, particularly in hard-to-understand areas.
• [N/A] I have run end-to-end tests tests and provided workload links above if applicable.
• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.