docs: fix linting

Signed-off-by: Luca Di Maio <[email protected]>

docs/posts/steamdeck_guide.md

@@ -1,9 +1,11 @@
 Latest SteamOS (version 3.5 and later) already pre-installed `distrobox` and `podman`.
 
 To run GUI application, add following line to `~/.distroboxrc`.
+
 ```sh
 xhost +si:localuser:$USER
 ```
+
 This is needed to ensure the graphical apps can talk to the Xwayland session.
 
 You can now start using `distrobox` on the deck, open the terminal and go:
@@ -15,7 +17,6 @@ distrobox create && distrobox enter
 Refer to the [quickstart guide](../README.md#quick-start) and to the [usage docs](../usage/usage.md)
 And don't forget the [useful tips](../useful_tips.md)!
 
-
 ## SteamOS 3.4 and earlier
 
 To install Distrobox on the steamdeck, we can install both `podman` and `distrobox`