[clang] [C23][N3006] Documented behavior of underspecified object declarations (PR #140911)

[Aaron Ballman via cfe-commits]

================
@@ -6454,3 +6454,51 @@ qualifications.
 Note, Clang does not allow an ``_Atomic`` function type because
 of explicit constraints against atomically qualified (arrays and) function
 types.
+
+
+Underspecified object declarations in C
----------------
AaronBallman wrote:

```suggestion
Underspecified Object Declarations in C
```

https://github.com/llvm/llvm-project/pull/140911