fbset: add page (#17653)

* Create fbset.md

pages/linux/fbset.md

@@ -0,0 +1,16 @@
+# fbset
+
+> Show and modify frame buffer device settings.
+> More information: <https://manned.org/man/fbset.1>.
+
+- Show current framebuffer settings:
+
+`sudo fbset {{[-i|--info]}}`
+
+- Set a framebuffer mode defined in `/etc/fb.modes`:
+
+`sudo fbset "{{800}}x{{600}}-{{60}}"`
+
+- Set an arbitrary framebuffer mode:
+
+`sudo fbset {{TTY_horizontal}} {{TTY_vertical}} {{monitor_horizontal}} {{monitor_vertical}} {{color_depth}}`