Updates architecture notes.

Author: jamie-lemon

docs/about.rst

@@ -88,10 +88,10 @@ Architecture
 
 |PyMuPDF| follows a four-layer system architecture with the following components:
 
-- **Python API Layer** - User-facing classes and functions
-- **Python Wrapper Layer** - High-level abstractions and utilities
-- **Binding Layer** - SWIG-generated wrapper for the MuPDF C++ API
-- **MuPDF Core Layer** - Native C/C++ implementation
+- **PyMuPDF Python API** - User-facing classes and functions
+- **MuPDF Python API** - Generated by SWIG
+- **MuPDF C++ API** -  Generated by custom tool and libclang
+- **MuPDF C API** - Native C/C++ implementation
 
 
 .. include:: version.rst