Remove trailing whitespaces in en/13.5.md

This is to prevent the following `gitbook build` error
with GitBook 2.0.1:

    Template render error: unexpected token: .
        (In file '13.5.md', Line 281, Column 10)

en/13.5.md

@@ -73,7 +73,6 @@ func (this *IndexController) Get() {
 ```
 
 
-	
 ViewController:
 
 ```