[clang-tools-extra] [clang-tidy] Rename google-readability-casting to modernize-avoid-c-style-cast (PR #171058)

[via cfe-commits]

================
@@ -3,12 +3,4 @@
 google-readability-casting
 ==========================
 
-Finds usages of C-style casts.
-
-https://google.github.io/styleguide/cppguide.html#Casting
-
-Corresponding cpplint.py check name: `readability/casting`.
-
-This check is similar to ``-Wold-style-cast``, but it suggests automated fixes
-in some cases. The reported locations should not be different from the
-ones generated by ``-Wold-style-cast``.
+The `google-readability-casting` check is an alias, please see `modernize-avoid-c-style-cast <../modernize/avoid-c-style-cast.html>`_ for more information.
----------------
zeyi2 wrote:

Please maintain 80 chars limit :)
```suggestion
The `google-readability-casting` check is an alias, please see 
`modernize-avoid-c-style-cast <../modernize/avoid-c-style-cast.html>`_ 
for more information.
```

https://github.com/llvm/llvm-project/pull/171058