~/.config/sway: Use a pretty background image

.config/sway/config

### Output configuration
#
# Default wallpaper (more resolutions are available in /usr/share/backgrounds/sway/)
output * bg /usr/share/backgrounds/sway/Sway_Wallpaper_Blue_1920x1080.png fill
output * bg /usr/share/backgrounds/gnome/Icetwigs.jpg fill
#
# Example configuration:
#