fix: print general commands in brackets

so that they appear in the top of a devshell message

Author: deemp

docs/src/modules_schema.md

@@ -97,7 +97,7 @@ and shown in the help menu.
 
 **Default value**:
 ```nix
-{"_type":"literalExpression","text":"\"general commands\""}
+{"_type":"literalExpression","text":"\"[general commands]\""}
 ```
 
 

modules/commands.nix

@@ -109,7 +109,7 @@ let
 
     category = mkOption {
       type = types.str;
-      default = "general commands";
+      default = "[general commands]";
       description = ''
         Set a free text category under which this command is grouped
         and shown in the help menu.