docs: Add more information about doxygen integration

docs/user_guide/doxygen_integration.md

@@ -1,5 +1,21 @@
 # Doxygen Integration
 
+## What
+
+`doxysphinx` is a package that handles integration
+of `Doxygen` and `Sphinx` documentation.
+
+`doxysphinx` allows displaying `Doxygen` documentation in the `Sphinx` documentation.
+
+`rocm-docs-core` applies some additional formatting and styling on top of this
+to stay in line with our themes.
+
+Since doxysphinx automatically integrates the Doxygen documentation,
+developers only have to update the documentation strings in the source code
+if they are formatted for Doxygen.
+
+## How
+
 Assuming Doxygen documentation is already configured correctly,
 call the `run_doxygen` method in the configuration file (`conf.py`)
 located in the `docs` folder.