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

[Erich Keane via cfe-commits]

================
@@ -998,25 +992,23 @@ headers to:
   ...
   #endif
 
-If the modules imported by your library provides such headers too, remember to add them to
-your ``your_library_imported.h`` too.
+If the modules imported by the library provide such headers, remember to add
+them to ``your_library_imported.h`` too.
 
 Importing modules
 ~~~~~~~~~~~~~~~~~
 
-When there are dependent libraries providing modules, we suggest you to import that in
-your module.
-
-Most of the existing libraries would fall into this catagory once the std module gets available.
+When there are dependent libraries providing modules, they should be imported
+in your module as well. Many existing libraries will fall into this catagory
+once the ``std`` module is more widely available.
 
 All dependent libraries providing modules
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Life gets easier if all the dependent libraries providing modules.
+Life gets easier if all the dependent libraries provide modules.
----------------
erichkeane wrote:

```suggestion
Of course, most of the complexity disappears if all the dependent libraries provide modules.
```

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