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

[Erich Keane via cfe-commits]

================
@@ -312,75 +300,76 @@ So all of the following name is not valid by default:
     __test
     // and so on ...
 
-If you still want to use the reserved module names for any reason, use
-``-Wno-reserved-module-identifier`` to suppress the warning.
+Using a reserved module name is strongly discouraged, but
+``-Wno-reserved-module-identifier`` can be used to suppress the warning.
 
-How to specify the dependent BMIs
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Specifying dependent BMIs
+~~~~~~~~~~~~~~~~~~~~~~~~~
 
-There are 3 methods to specify the dependent BMIs:
+There are 3 ways to specify a dependent BMI:
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erichkeane wrote:

WTF is a dependent BMI?

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