[clang] Revise the modules document for clarity (PR #90237)

[Chuanqi Xu via cfe-commits]

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@@ -577,15 +574,16 @@ the generated BMI specified by ``-o`` will be full BMI and the BMI specified by
                                                -> ...
                                                -> consumer_n.cpp
 
-We don't emit diagnostics if ``-fexperimental-modules-reduced-bmi`` is used with a non-module
-unit. This design helps the end users of one phase compilation model to perform experiments
-early without asking for the help of build systems. The users of build systems which supports
-two phase compilation model still need helps from build systems.
+Clang does not emit diagnostics when ``-fexperimental-modules-reduced-bmi`` is
+used with a non-module unit. This design helps the end users of the one-phase
+compilation model to perform experiments without needing to modify the build
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ChuanqiXu9 wrote:

Or try Reduced BMI?

https://github.com/llvm/llvm-project/pull/90237