update readme

## 界面说明及快捷键

* Ctrl+Z, Ctrl+Y可以撤销重做大部分操作，注意翻页后撤消重做栈会清空

* A/D翻页, 如果当前页面未保存会自动保存

* A/D或pageUp/Down翻页, 如果当前页面未保存会自动保存

* "T"切换到文本编辑模式下(底部最右"T"图标), W激活文本块创建模式后在画布右键拉文本框

* "P"切换到画板模式, 右下角滑条改原图透明度

* 底部左侧"OCR"和"A"按钮控制启用/禁用OCR翻译功能, 禁用后再Run程序就只做文本检测和抹字  

</p>

## Shortcuts

* A/D to turn the page

* A/D or pageUp/Down to turn the page

* Ctrl+Z, Ctrl+Y to undo/redo most operations, note the undo stack will be cleared after you turn the page.

* T to text-editting mode, (or the "T" button on the bottom toolbar) press W to activate text block creating mode, then drag the mouse on the canvas with the right button clicked to add a new text block. (see the text editing gif)

* P to image-editting mode.