update readme

Author: dnblank123

README.md

@@ -1,2 +1,8 @@
 ## The issue in Dragon Nest
 The game has a particle bug on the AMD CPU after the 64-bit release. This fork fixes it.
+
+## Why use this
+.pak need to update when dnshader changes (dnshaders2.dat). The dll only needs to check if the specific shader is still the same hash. So updating the dll will be "rarely".
+
+## Note
+Simplified in this context is less instruction count and hopefully less GPU usage.