README: Add animated demo

Includes source files, and script for generating the animation.

README.md

@@ -105,11 +105,9 @@ When installing the O/S via $ZFS_OS_INSTALLATION_SCRIPT, the root pool is mounte
 
 Other options may be supported, and displayed in the current commandline help, so users are invited to take a look.
 
-## Screenshots
+## Demo
 
-![Devices selection](/screenshots/01-devices_selection.png?raw=true)
+![Demo](/demo/demo.gif?raw=true)
-![Encryption](/screenshots/02-encryption.png?raw=true)
-![Boot pool tweaks](/screenshots/03-boot_pool_tweaks.png?raw=true)
 
 ## Bug reporting/feature requests
 

demo/source/convert.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+source_dir=$(readlink -f $(dirname "$0"))
+demo_dir=$(dirname "$source_dir")
+
+(for f in "$source_dir"/*.webm; do echo "file '$f'"; done) | ffmpeg -f concat -safe 0 -i /dev/stdin -vf "fps=2,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" "$demo_dir/demo.gif" -y