[Bug libstdc++/66792] Document sort template in bits/list.tcc

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66792
Bug 66792 depends on bug 66742, which changed state.

Bug 66742 Summary: abort on sorting list with custom allocator that is not 
stateless
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66742

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |---