Document that an enum class can be considered a Map

For the purpose of calling keys, values, kv, pairs, antipairs, invert
methods.

Author: lizmat

doc/Type/Enumeration.rakudoc

@@ -71,9 +71,34 @@ enum Foo <bar baz>;
 say baz ~~ Foo;  # OUTPUT: «True␤»
 say Foo ~~ bar;  # OUTPUT: «False␤»
 
-=head1 Methods
+=head1 Methods that work on the enum class
+
+As of release 2021.04 of the Rakudo compiler, an enum class can be
+considered as an instantiated L<Map|/type/Map> object.  This means
+you can use the
+L<keys|type/Map#method_keys>,
+L<values|type/Map#method_values>,
+L<kv|type/Map#method_kv>,
+L<pairs|type/Map#method_pairs>,
+L<antipairs|type/Map#method_antipairs>,
+L<invert|type/Map#method_invert>
+on an enum class and get the expected result.
 
-These are the methods included in this role:
+    enum Norse-gods <Þor Oðin Freija>;
+    say Nors-gods.keys; # OUTPUT: «(Þor Oðin Freija)␤»
+
+=head2 method enums
+
+    method enums()
+
+Returns a L<Map|/type/Map> of enum values. Works both on the enum type
+and any key.
+
+    enum Mass ( mg => 1/1000, g => 1/1, kg => 1000/1 );
+    say Mass.enums; # OUTPUT: «Map.new((g => 1, kg => 1000, mg => 0.001))␤»
+    say g.enums;    # OUTPUT: «Map.new((g => 1, kg => 1000, mg => 0.001))␤»
+
+=head1 Methods that work on the enum keys
 
 =head2 method key
 
@@ -82,7 +107,6 @@ An C<Enumeration> property.
     enum Norse-gods <Þor Oðin Freija>;
     say Freija.key; # OUTPUT: «Freija␤»
 
-
 =head2 method value
 
 These are C<Enumeration> properties.
@@ -93,17 +117,6 @@ These are C<Enumeration> properties.
 The C<value> is assigned automatically by the C<enum> type starting at 0.
 C<Oðin> gets 1 since it is the second in the C<enum>.
 
-=head2 method enums
-
-    method enums()
-
-Returns a L<Map|/type/Map> of enum values. Works both on the enum type
-and any key.
-
-    enum Mass ( mg => 1/1000, g => 1/1, kg => 1000/1 );
-    say Mass.enums; # OUTPUT: «Map.new((g => 1, kg => 1000, mg => 0.001))␤»
-    say g.enums;    # OUTPUT: «Map.new((g => 1, kg => 1000, mg => 0.001))␤»
-
 =head2 method kv
 
     multi method kv(::?CLASS:D:)