swaybg: add page (#11533)

* new swaybg page

* revivew changes

* review changes 2

* review 3

pages/linux/swaybg.md

@@ -0,0 +1,16 @@
+# swaybg
+
+> Wallpaper tool for Wayland compositors.
+> More information: <https://github.com/swaywm/swaybg/blob/master/swaybg.1.scd>.
+
+- Set the wallpaper to an [i]mage:
+
+`swaybg --image {{path/to/image}}`
+
+- Set the wallpaper [m]ode:
+
+`swaybg --image {{path/to/image}} --mode {{stretch|fit|fill|center|tile|solid_color}}`
+
+- Set the wallpaper to a static [c]olor:
+
+`swaybg --color {{"#rrggbb"}}`