[clang] [clang] Add sections to C++ DR status page (PR #165749)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

Looking at this 
<img width="1704" height="304" alt="image" src="https://github.com/user-attachments/assets/5bb518b4-b7c2-48d4-9deb-ca1c21bd6cd9" />
I'm not sure that combining the columns will help enough to save horizontal space, but it will come at the expense of readability of stable names as pointed out [on the CWG reflector](http://lists.isocpp.org/core/2025/10/18649.php). Maybe we should drop section numbers instead?

https://github.com/llvm/llvm-project/pull/165749