fix the switch example.

Author: Break Yang

README.md

@@ -262,6 +262,7 @@ format and focus on more important stuff.
  is huge enough to compensate the loss.
 1. `auto` is permitted when it promotes readability.
 1. `switch` cases may have scopes:
+
  ```c++
  switch (var) {
   case 0: { // 2 space indent