docs:cursor style option

docs/guide/option.md

@@ -51,5 +51,6 @@ interface IEditorOption {
   watermark?: IWatermark; // 水印信息。{data:string; color?:string; opacity?:number; size?:number; font?:string;}
   control?: IControlOption; // 控件信息。 {placeholderColor?:string; bracketColor?:string; prefix?:string; postfix?:string;}
   checkbox?: ICheckboxOption; // 复选框信息。{width?:number; height?:number; gap?:number; lineWidth?:number; fillStyle?:string; fontStyle?: string;}
+  cursor?: ICursorOption; // 光标样式。{width?: number; color?: string; dragWidth?: number; dragColor?: string;}
 }
 ```