[clang] [Doc] Update documentation for no-transitive-change (PR #96453)

[Chuanqi Xu via cfe-commits]

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@@ -652,6 +652,134 @@ in the future. The expected roadmap for Reduced BMIs as of Clang 19.x is:
    comes, the term BMI will refer to the Reduced BMI and the Full BMI will only
    be meaningful to build systems which elect to support two-phase compilation.
 
+Experimental No Transitive Change
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ChuanqiXu9 wrote:

> Is it actually experimental if it's the default and there is no way to disable it?

This experiment can only be performed with the build systems. There shouldn't be any risk if the build systems implemented transitive changes model already. In another word, what I did actually provides an opportunity to the build systems to implement this feature. So ideally, the users should be able to disable it in the build system level.

> I suggest saying "initial", would it better to capture what we intend to do (I suspect we want to keep improving this and want feedback where it falls short)?

Yes that we want to keep improving this and want feedback where it falls short. I used `experimental` since I want to mention this feature may not be stable. It might be problematic that some recompilations got skipped but they shouldn't. So that users should go back to traditional mode in such cases. Then I feel `experimental` sounds good for such situations.

https://github.com/llvm/llvm-project/pull/96453