update screenshot with demo.gif

Author: chiefjester

README.md

@@ -5,7 +5,7 @@ Path navigator designed to work with Vim's built-in mechanisms and
 [complementary](https://github.com/tpope/vim-eunuch)
 [plugins](https://github.com/tpope/vim-unimpaired).
 
-<img src="./dirvish.png" alt="dirvish" width="400"/>
+<img src="./demo.gif" alt="dirvish" width="452"/>
 
 Features
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@@ -19,6 +19,7 @@ Features
 - _Powerful:_ `:Shdo[!]` generates shell script
 - _Reliable:_ Less code, fewer bugs (96% smaller than netrw). Supports Vim 7.2+
 
+
 Concepts
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