[clang-tools-extra] Fix typos in Modularize.rst (llvm#99256)

mainly, fixed “the Clang module mechanism doesn’t support headers the
rely on other headers” => “the Clang module mechanism doesn’t support
headers that rely on other headers”. [emphasis on “the” versus “that”]

Author: Abe149

clang-tools-extra/docs/modularize.rst

@@ -254,8 +254,8 @@ For example, with the same header list from above::
   }
 
 Note that headers with dependents will be ignored with a warning, as the
-Clang module mechanism doesn't support headers the rely on other headers
-to be included first.
+Clang module mechanism doesn't support headers that rely on other headers
+being included first.
 
 The module map format defines some keywords which can't be used in module
 names. If a header has one of these names, an underscore ('_') will be