nixpkgs/elvish: load carapace completion

.config/nixpkgs/elvish/lib/config.elv

@@ -35,6 +35,8 @@ set edit:after-command = [{|m|
   }
 }]
 
+eval (carapace _carapace|slurp)
+
 # import local.elv if present, for example, from ~/.config/elvish/lib/local.elv
 try {
   use local