Fix Read the Docs badge build

[Gonza10V]

Motivation

• The Read the Docs badge in the README was failing even though documentation exists because RTD was not configured to use the repository's docs and the Sphinx/AutoAPI settings were not compatible with the RTD build environment.
• AutoAPI was pointed at a non-existing path and Sphinx pins were outdated which caused the docs build to fail on RTD.
• A few malformed reStructuredText/docstrings produced Sphinx errors that prevented a clean documentation build.

Description

• Add a Read the Docs v2 configuration file .readthedocs.yaml that instructs RTD to use docs/conf.py, install docs/requirements.txt, and install the package before building.
• Update docs/requirements.txt to use Sphinx/RTD/AutoAPI versions compatible with the RTD build image (pinned to sphinx==7.4.7, sphinx_rtd_theme==2.0.0, sphinx-autoapi==3.6.0).
• Point AutoAPI at the real package path by changing autoapi_dirs in docs/conf.py from ['../loica'] to ['../src/loica'] and disable the missing _static path by setting html_static_path = [].
• Clean up README links (fix the documentation badge target and docs URL) and fix a few Sphinx/source issues in docs/index.rst, src/loica/sample.py, and src/loica/geneproduct.py to remove docstring/reST problems.

Testing

• Installed the pinned docs deps and ran cd docs && make html, and the Sphinx build completed successfully with the HTML output generated (the build emitted warnings from AutoAPI about duplicate objects but exited successfully).
• Changes were committed and are ready to be pushed so RTD can rebuild using the new .readthedocs.yaml configuration.

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Codex Task