Merge branch 'usage_statements'

With usage statements for Enum.pod

lib/Type/Enum.pod

@@ -13,20 +13,38 @@ C<Pair> (which inherits from Enum).
 
 =head2 method key
 
+Defined as:
+
     multi method key(Enum:D:)
 
+Usage:
+
+    ENUM.key
+
 Returns the key part of the Enum.
 
 =head2 method value
 
+Defined as:
+
     multi method value(Enum:D:)
 
+Usage:
+
+    ENUM.value
+
 Returns the value part of the Enum.
 
 =head2 method invert
 
+Defined as:
+
     multi method invert(Enum:D:) returns Enum:D
 
+Usage:
+
+    ENUM.invert
+
 Returns a new C<Enum> with the original enum's value as the key, and the
 original enum's key as value.