Fixup module

Author: timriley

docsite/source/optional-values.html.md

@@ -11,6 +11,8 @@ Types themselves have optional attributes you can apply to get further functiona
 By default, nil values raise an error:
 
 ``` ruby
+Types = Dry.Types()
+
 Types::Strict::String[nil]
 # => raises Dry::Types::ConstraintError
 ```