Merge pull request #41712 from cabmeurer/cxx-interop/Fix-typo-update-example-cxx-module

 [cxx-interop] Fix typo in getting started, and update example for creating the cxx module

Author: zoecarver

docs/CppInteropability/GettingStartedWithC++Interop.md

@@ -59,24 +59,23 @@ struct ContentView: View {
 ```
 
 ```
-//In Cxx.cpp
+//In Cxx.hpp
+
+#ifndef Cxx_hpp
+#define Cxx_hpp
 
-#include "Cxx.hpp"
 int cxxFunction(int n) {
     return n;
 }
-
+#endif
 ```
 
 ```
-//In Cxx.hpp
-
-#ifndef Cxx_hpp
-#define Cxx_hpp
+//In Cxx.cpp
 
+#include "Cxx.hpp"
 int cxxFunction(int n);
 
-#endif
 
 ```
 
@@ -198,7 +197,7 @@ CxxInterop.main()
 
 ```
 
-- In your projects direcetoy, run `cmake` to generate the systems build files
+- In your project's directory, run `cmake` to generate the systems build files
 
 - To generate an Xcode project run `cmake -GXcode` 
 - To generate with Ninja run `cmake -GNinja`