Reference to clang.cindex?

[EricCousineau-TRI]

Is it possible have a documented reference to clang.cindex?
https://github.com/llvm/llvm-project/blob/6792069a3fdb412d06dd3cc42a6181c6fb7db860/clang/bindings/python/clang/cindex.py

It's basically some simple Python bindings (using cdll) to interface with libclang:
https://github.com/llvm/llvm-project/blob/6792069a3fdb412d06dd3cc42a6181c6fb7db860/clang/bindings/python/clang/cindex.py#L4171-L4178

Perhaps it'd be useful to have a brief comparison of why CastXML is better than libclang?
(and also some places where libclang has more info than CastXML, like templates, comments, etc.?)

Relates:

• mkdoc: Should swap clang.cindex backend out with pygccxml RobotLocomotion/drake#13670
• Extract comments in header files CastXML#152
• Add structured support for templates? CastXML#171
• attributes: How to access [[deprecated(str)]]? #122

(I wanted to post this in CastXML, but I dunno if it's the right place...)