docs: Update configs for documentation to host on Read the Docs

[peterjunpark]

Motivation

• Use ROCm docs theme
• Add Read the Docs config

Technical Details

Test Plan

Test Result

Submission Checklist

• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

[Copilot]

Pull request overview

This PR updates the Sphinx documentation configuration to use the ROCm docs theme and introduces Read the Docs configuration/dependency pinning to enable hosting docs builds on RTD.

Changes:

• Switch docs/conf.py to rocm_docs_theme / rocm_docs extension and introduce external ToC + version substitution.
• Add RTD build config and a pinned Sphinx requirements set (requirements.in + compiled requirements.txt).
• Replace the landing-page toctree structure with an external _toc.yml-driven nav, and remove the old tutorials index page.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
docs/conf.py	Switches to ROCm docs theme/extension; adds external ToC + version substitution.
docs/index.rst	Updates index title/content to rely on external ToC navigation.
docs/sphinx/_toc.yml.in	Adds an external ToC structure for site navigation.
docs/sphinx/requirements.in	Introduces minimal input requirements for doc builds.
docs/sphinx/requirements.txt	Adds pip-compiled, fully pinned doc build dependencies.
docs/.readthedocs.yaml	Adds RTD build configuration.
docs/kernel_authoring_guide.md	Fixes an internal anchor link to match generated heading ID.
docs/tutorials/index.rst	Removes the old tutorials landing page (previously used by toctree).
.gitignore	Ignores generated _toc.yml.

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[peterjunpark]

Preview: https://rocm.docs.amd.com/projects/FlyDSL/en/latest/