Move decorator definition

numbat/src/parser.rs

@@ -10,11 +10,12 @@
 //! fn_decl_generic →   "<" ( identifier "," ) * identifier ">"
 //! fn_decl_param   →   "(" ( identifier ( ":" type_annotation ) ? "," )* ( identifier ( ":" type_annotation ) ) ? ")"
 //! dimension_decl  →   "dimension" identifier ( "=" dimension_expr ) *
-//! decorator       →   "@" ( "metric_prefixes" | "binary_prefixes" | ( "aliases(" list_of_aliases ")" ) )
 //! unit_decl       →   decorator * "unit" ( ":" dimension_expr ) ? ( "=" expression ) ?
 //! procedure_call  →   ( "print" | "assert_eq" | "type" ) "(" arguments? ")"
 //! module_import   →   "use" ident ( "::" ident) *
 //!
+//! decorator       →   "@" ( "metric_prefixes" | "binary_prefixes" | ( "aliases(" list_of_aliases ")" ) )
+//!
 //! dimension_expr  →   dim_factor
 //! dim_factor      →   dim_power ( (multiply | divide) dim_power ) *
 //! dim_power       →   dim_primary ( power dim_exponent | unicode_exponent ) ?