README-winrt.md: Cleaned up sample code

- Fixed the markdown.
- Code can now be exited by pressing ESC.
- Cleans up and returns from main()
- Mushed all the `if (x) { return 0; }` blocks into else ifs.

docs/README-winrt.md

@@ -352,38 +352,41 @@ source file, such as, "main.cpp".
 your project, and open the file in Visual C++'s text editor.
 7. Copy and paste the following code into the new file, then save it.
 
+```c
+#include <SDL.h>
     
-    #include <SDL.h>
-    
-    int main(int argc, char **argv)
-    {
+int main(int argc, char **argv)
+{
     SDL_DisplayMode mode;
     SDL_Window * window = NULL;
     SDL_Renderer * renderer = NULL;
     SDL_Event evt;
+    SDL_bool keep_going = SDL_TRUE;
   
     if (SDL_Init(SDL_INIT_VIDEO) != 0) {
         return 1;
-        }
-    
-        if (SDL_GetCurrentDisplayMode(0, &mode) != 0) {
+    } else if (SDL_GetCurrentDisplayMode(0, &mode) != 0) {
+        return 1;
+    } else if (SDL_CreateWindowAndRenderer(mode.w, mode.h, SDL_WINDOW_FULLSCREEN, &window, &renderer) != 0) {
         return 1;
     }
     
-        if (SDL_CreateWindowAndRenderer(mode.w, mode.h, SDL_WINDOW_FULLSCREEN, &window, &renderer) != 0) {
-            return 1;
-        }
-    
-        while (1) {
+    while (keep_going) {
         while (SDL_PollEvent(&evt)) {
+            if ((evt.type == SDL_KEYDOWN) && (evt.key.keysym.sym == SDLK_ESCAPE)) {
+                keep_going = SDL_FALSE;
+            } 
         }
     
         SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
         SDL_RenderClear(renderer);
         SDL_RenderPresent(renderer);
     }
-    }
 
+    SDL_Quit();
+    return 0;
+}
+```
 
 #### 6.B. Adding code and assets ####