feat: 更新 mods.toml 和 README.md

- 在 mods.toml 中添加 mod 图标文件
- 在 README.md 中添加本地化实现说明

Author: TexBlock

README.md

@@ -1,3 +1,17 @@
+<img height="120" src="src/main/resources/icon.png" width="120"/>
+
 # Checklist Localizer
 Make Checklist Mod support task localization!
 
+You can localize it in the following ways:
+First, create a new language file (e.g. `en_us.json`).
+Then you can use the text contents of `tasks.txt` as a translation key to write the language file. As shown below:
+```json
+{
+  "Example Title": "Localized Title",
+  "Task 1": "Localized Task 1",
+  "Task 2": "Localized Task 2"
+}
+```
+
+Finally you'll be able to load it into the resource pack and load the resource pack in the game.