[clang-tools-extra] [clang-tidy] Improve readability-enum-initial-value diagnostic message (PR #176485)

[via cfe-commits]

================
@@ -15,6 +15,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
----------------
zeyi2 wrote:

Seems like unnecessary header include?
```suggestion
```

https://github.com/llvm/llvm-project/pull/176485