Add initial Sphinx documentation setup with API reference

[Chaitanya-Parab]

Describe your changes

Description
Added an initial Sphinx-based documentation setup for the project:

1. Created a docs/ directory with Sphinx configuration.
2. Enabled autodoc and napoleon extensions for automatic API documentation generation from docstrings.
3. Added a basic index.rst as the main entry point.
4. Created an api.rst file and linked it in the toctree for proper navigation.
5. Verified that documentation builds successfully locally.

Motivation & Context:
As the project grows, the current README-based documentation becomes harder to navigate. This change introduces a
structured and scalable documentation system, making it easier to maintain and extend documentation in the future.

Dependencies:
1. sphinx
2. sphinx-rtd-theme (optional for better UI)

Issue Link

Closes #61

Type of change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [🗸] 📖 Documentation (Addition or improvements to documentation)

Checklist before requesting a review

• [🗸 ] My branch is up-to-date with the target branch - if not update your fork with the changes from the target branch (use pull with --rebase option if possible).
• [ 🗸] I have performed a self-review of my code
• [ 🗸] For any new/modified functions/classes I have added docstrings that clearly describe its purpose, expected inputs and returned values
• [🗸] I have placed in-line comments to clarify the intent of any hard-to-understand passages of my code
• I have updated the README to cover introduced code changes
• I have added tests that prove my fix is effective or that my feature works
• [🗸 ] I have given the PR a name that clearly describes the change, written in imperative form (context).
• I have requested a reviewer and an assignee (assignee is responsible for merging). This applies only if you have write access to the repo, otherwise feel free to tag a maintainer to add a reviewer and assignee.

Checklist for reviewers

Each PR comes with its own improvements and flaws. The reviewer should check the following:

• the code is readable
• the code is well tested
• the code is documented (including return types and parameters)
• the code is easy to maintain

Author checklist after completed review

• I have added a line to the CHANGELOG describing this change, in a section
  reflecting type of change (add section where missing):
  • added: when you have added new functionality
  • changed: when default behaviour of the code has been changed
  • fixes: when your contribution fixes a bug
  • maintenance: when your contribution is relates to repo maintenance, e.g. CI/CD or documentation

Checklist for assignee

• PR is up to date with the base branch
• the tests pass
• (if the PR is not just maintenance/bugfix) the PR is assigned to the next milestone. If it is not, propose it for a future milestone.
• author has added an entry to the changelog (and designated the change as added, changed, fixed or maintenance)
• Once the PR is ready to be merged, squash commits and merge the PR.

[sadamov]

this is a duplicate of #272 and #252

[Chaitanya-Parab]

Thanks for pointing that out!

I’ll go through #272 and #252 to better understand the existing work and see how I can contribute there instead of duplicating efforts.

Happy to help improve or build on the existing approach.