Use imgur-hosted welcome GIF

Author: 3noch

README.md

@@ -4,7 +4,7 @@
 
 Build terminal applications using functional reactive programming (FRP) with [Reflex FRP](https://reflex-frp.org).
 
-![reflex-vty example animation](doc/welcome.gif)
+![Example Animation](https://i.imgur.com/FULQNtu.gif)
 
 Feature requests, pull requests, and other feedback are welcome and appreciated (see the [contribution guide](CONTRIBUTING.md)). This library
 is still experimental, so big changes are possible!

doc/welcome.gif

@@ -15,8 +15,7 @@ build-type: Simple
 cabal-version: >=1.18
 extra-source-files: README.md
                     ChangeLog.md
-extra-doc-files: doc/welcome.gif
-               , doc/tasks.png
+extra-doc-files: doc/tasks.png
 tested-with: GHC ==8.8.3 || ==8.6.5 || ==8.4.4
 
 library