Sphinx Python Documentation (#1567) - Revised index.rst.

Changed index page title, added introduction text, and changed the
order of Python modules, to reflect the order in which support for the
different shading languages was added to MaterialX.

documents/DeveloperGuide/index.rst

@@ -1,5 +1,23 @@
-MaterialX Developer Guide
-=========================
+MaterialX Python API Documentation
+==================================
+
+The MaterialX Python API provides Python bindings for the
+`MaterialX C++ API <https://materialx.org/docs/api/>`_ .
+
+MaterialX is an open standard for representing rich material and look-development
+content in computer graphics, enabling its platform-independent description and
+exchange across applications and renderers. Launched at `Industrial Light & Magic
+<https://www.ilm.com/>`_ in 2012, MaterialX has been a key technology in their
+feature films and real-time experiences since *Star Wars: The Force Awakens*
+and *Millennium Falcon: Smugglers Run*. The project was released as open source
+in 2017, with companies including Sony Pictures Imageworks, Pixar, Autodesk,
+Adobe, and SideFX contributing to its ongoing development. In 2021, MaterialX
+became the seventh hosted project of the `Academy Software Foundation
+<https://www.aswf.io/>`_ .
+
+General information about MaterialX, announcements, events, third-party support,
+and contributing to MaterialX is available at
+`MaterialX.org <https://materialx.org/>`_ .
 
 .. toctree::
     :maxdepth: 1
@@ -19,15 +37,15 @@ MaterialX Python Modules
 
     PyMaterialXCore
     PyMaterialXFormat
+    PyMaterialXGenShader
     PyMaterialXGenGlsl
+    PyMaterialXGenOsl
     PyMaterialXGenMdl
     PyMaterialXGenMsl
-    PyMaterialXGenOsl
-    PyMaterialXGenShader
     PyMaterialXRender
     PyMaterialXRenderGlsl
-    PyMaterialXRenderMsl
     PyMaterialXRenderOsl
+    PyMaterialXRenderMsl
 
 
 Import Order Dependencies