Doom: Add xonsh-mode

doom/packages.el

@@ -38,6 +38,7 @@
 ;; If you'd like to disable a package included with Doom, for whatever reason,
 ;; you can do so here with the `:disable' property:
 (package! coffee-mode :disable t)
+(package! xonsh-mode)
 
 ;; You can override the recipe of a built in package without having to specify
 ;; all the properties for `:recipe'. These will inherit the rest of its recipe