README: add screencast for edit experience

README.md

@@ -53,6 +53,8 @@ Utilizing Qt, VNote could run on **Linux**, **Windows**, and **macOS** (due to t
 - Supports [Mermaid](http://knsv.github.io/mermaid/), [Flowchart.js](http://flowchart.js.org/), and [MathJax](https://www.mathjax.org/);
 - Supports HiDPI.
 
+![VNote Edit](screenshots/vnote_edit.gif)
+
 # Why VNote
 ## Markdown Editor & Notes Management
 VNote tries to be a powerful Markdown editor with notes management, or a note-taking application with pleasant Markdown support. If you are a fan of Markdown and enjoy writing Markdown notes for study, work, and life, VNote is the right tool for you.

README_zh.md

@@ -52,6 +52,8 @@ VNote不是一个简单的Markdown编辑器。通过提供笔记管理功能，V
 - 支持[Mermaid](http://knsv.github.io/mermaid/), [Flowchart.js](http://flowchart.js.org/) 和 [MathJax](https://www.mathjax.org/);
 - 支持高分辨率；
 
+![VNote Edit](screenshots/vnote_edit.gif)
+
 # 开发VNote的动机
 ## Markdown编辑器与笔记管理
 VNote设计为带有笔记管理功能的Markdown编辑器，或者有良好Markdown支持的笔记软件。如果您喜欢Markdown并经常在学习、工作和生活中使用Markdown记录笔记，那么VNote就是一个适合您的工具。