Turn references to listings in the text link to the actual listing

One small annoyance when reading through this book is that every now and then there will be some text that says "in Listing X-Y we [...]" that refers to a listing from some earlier chapter. These references to previous listings are just plain text, not links, and so you'll have to find the listing manually. Since the listings aren't numbered by section, but by chapter, it's also not easy to know which specific segment of the chapter this listing is from. If it says 4-13, I don't know if that's going to be in chapter 4.1, 4.2 or 4.3. As such, finding the listing referred to isn't very inconvenient.

Usually the contents of that listing is relevant context in order to fully understand the points being made in the text, so sometimes it might help to refresh your memory of the code from that listing by going back to read it again. Most people won't remember much about the code being talked about when it's code they read 10 chapters ago, after all.

So, I propose turning these into links that take you to the actual listing. Each listing already has a working link in its description text, so the links are already there and functional. Should be a simple matter of just going through the text and replacing all plain text references to listings with links to said listing.

The issue identifies plain-text references such as “Listing X-Y” in the book text, and says each listing description already has a working link. Start by locating those references and inspecting the existing listing links; done means every reference links to its corresponding listing and the book’s links remain valid.