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

[Chuanqi Xu via cfe-commits]

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@@ -652,6 +652,141 @@ 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
+---------------------------------
+
+This section is primarily for build system vendors. For end compiler users,
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ChuanqiXu9 wrote:

Yeah, added suggested text. 

For bazel, I think it might be fine since it should be configurable that whether not to recompile a target as far as I know.

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