Add initial API documentation (docstrings) for ToolkitHome and core toolkit interfaces

[ilayfalach]

This issue tracks the addition of clear and structured docstrings to the public API of the Hera toolkit system.

The goal is to document what each user-facing function does, including its purpose, inputs, outputs, and expected behavior, so that:

Developers can understand and use the API more easily.

Existing Sphinx infrastructure can automatically generate accurate API documentation.

The current and future codebase has a consistent documentation standard.

The initial focus is on core entry points such as ToolkitHome and abstractToolkit, covering only user-facing methods. Internal helpers and private logic are intentionally excluded at this stage.

This issue is part of a larger effort to validate and (re)enable Sphinx-based API documentation for the entire system, with future issues expected to expand coverage.

[ilayfalach]

Toolkit API Documentation Update

This change adds a new Sphinx documentation page for the Toolkit API, which did not exist before, and standardizes the public API docstrings in toolkit.py.

What was done

Created a new Sphinx RST file that builds the Toolkit API page and connected it to the main index.rst.

Added and refined English-only, Sphinx-compatible docstrings for the public Toolkit API:

ToolkitHome

abstractToolkit

Core methods such as:
getToolkit, registerToolkit, getToolkitDocuments,
auto_register_and_get, and the data source APIs.

Enforced a clear and consistent docstring structure:

Short summary line

Detailed description

Explicit Parameters, Returns, and Raises sections

Verified that the new page is successfully generated and rendered using Sphinx autodoc.

How to view the new Toolkit API page
cd hera/hera/doc/sphinx
make clean
make html
xdg-open _build/html/index.html

Then navigate to:
Toolkit API → hera.toolkit → ToolkitHome / abstractToolkit

Documentation conventions

Public API only.

English documentation only.

Docstrings written specifically for Sphinx autodoc (pydoc style).

The structure is intended to be reused for documenting additional modules.

This change introduces the first dedicated Toolkit API documentation page and establishes a clean, extensible foundation for future documentation work. @yehudarav