Update README.md

Author: sr4dev

README.md

@@ -84,8 +84,8 @@ This extension uses AssetImporter.userData of Texture asset. If your project alr
 Unity Document: [AssetImporter.userData](https://docs.unity3d.com/ScriptReference/AssetImporter-userData.html)
 
 ### Known Issues
+- Does not support SpriteAtlas.
 - Does not support PSD file.
-- Import time may be significantly longer or may not complete in Unity 6.
 
 For other issues, please refer to the link.
 https://github.com/sr4dev/Unity-SpriteAssist/issues