[clang-tools-extra] [clang-tidy][doc][NFC] extract common global options in doc (PR #119842)

[Congcong Cai via cfe-commits]

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@@ -0,0 +1,21 @@
+==============
+Global Options
+==============
+
+Some options apply to multiple checks. This page lists all the available
+globally options.
+
+.. option:: IncludeStyle
+
+   A string specifying which include-style is used, `llvm` or `google`. Default
+   is `llvm`.
+
+.. option:: IgnoreMacros
----------------
HerrCai0907 wrote:

according to current implement of clangtidy, lots of checks will read ignores macros from global scope. i don't think it is a good idea to change lots of checks behavior.

maybe i can notices something in this file to explain global option doesn't apply from every check?

https://github.com/llvm/llvm-project/pull/119842