[clang-tools-extra] [clang-tidy] Update google todo checker with style guide changes. (PR #165565)

[Congcong Cai via cfe-commits]

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@@ -9,3 +9,14 @@ The relevant style guide section is
 https://google.github.io/styleguide/cppguide.html#TODO_Comments.
 
 Corresponding cpplint.py check: `readability/todo`
+
+Options
+-------
+
+.. option:: Style
+
+   A string specifying the TODO style for fix-it hints. Accepted values are
+   `Hyphen` and `Parentheses`. Default is `Hyphen`.
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HerrCai0907 wrote:

what should be the default value could be a good question.

https://github.com/llvm/llvm-project/pull/165565