Documentation prototype and ReadtheDocs CI

[bstefanuk]

This PR adds a prototype documentation site, along with necessary CI files, for hosting Tensile docs with ROCm styling. Currently, the docs are structured with a proposed format using placeholder files.

Local build steps:

1. Create a virtual environment: python3 -m venv .venv && source .venv/bin/activate
2. Install the Python packages needed to build the docs: pip3 install -r docs/sphinx/requirements.txt
3. Build the docs:

   cd docs
   python3 -m sphinx -T -b html -d _build/doctrees -D language=en . _build/html

4. Find the built docs in _build/html/

Notes:

• Each PR will build the documentation site as a job titled: docs/readthedocs.com:[project-id]

[ellosel]

This change set establishes a base sphinx docs structure that conforms to amd docs style etc and automates generation and deployment of the docs. There are no changes to any of the Tensile code and should not impact the correctness or efficiency of the existing production code. Approve pending pipelines