Update readme

Author: Aixile

README.md

@@ -8,11 +8,12 @@
 
 ##ダウンロード
 
-[Etupirka-0.5.1.zip](http://etupirka.halcyons.org/download/Etupirka-0.5.1.zip "Etupirka-0.5.1.zip")
+[Etupirka-0.5.1.zip](http://etupirka.halcyons.org/download/Etupirka-0.5.2.zip "Etupirka-0.5.2.zip")
 
 [Mirror](https://github.com/Aixile/Etupirka/releases "https://github.com/Aixile/Etupirka/releases")
 
 
+0.5.2: Optimized
 0.5.1: Fix crashing on startup
 
 ##使い方