docs: convert index.rst to MyST .md (#294)

Converts docs/index.rst to docs/index.md and adds `myst_parser` to
the Sphinx extensions list (the docs were RST-only previously).
The single index page is a thin wrapper around the README.

Part of PyAutoLabs/PyAutoFit#1245.

Co-authored-by: Jammy2211 <[email protected]>
Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>

Author: 3 people

docs/conf.py

@@ -39,6 +39,7 @@
     "sphinx.ext.napoleon",
     "sphinx.ext.extlinks",
     "numpydoc",
+    "myst_parser",
 ]
 
 ## Generate autodoc stubs with summaries from code

docs/index.md

@@ -0,0 +1,3 @@
+```{eval-rst}
+.. include:: ../README.rst
+```