Property-Based Testing with PropEr, Erlang, and Elixir: Link is out of date (page 182)

@ferd

Link to the paragraph of the Erlang documentation “7.3 Type Declarations of User-Defined Types” is out of date.
Current link is https://www.erlang.org/doc/reference_manual/typespec.html#type-declarations-of-user-defined-types