installation.md redundant backtick (vuejs#784)

Alex-Sokolov · kazupon · commit f510f5846308 · 2017-02-27T18:27:27.000+09:00
diff --git a/src/v2/guide/installation.md b/src/v2/guide/installation.md
@@ -119,7 +119,7 @@ module.exports = {
     }
   }
 }
-````
+```
 
 #### Rollup
 
