Add link to Debug trait

[swaroopch]

I don't recall reading about this Debug trait so far in the book. Please ignore this PR if I have missed that part.

r? @steveklabnik

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @steveklabnik (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. The way Github handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see CONTRIBUTING.md for more information.

[steveklabnik]

Thanks @swaroopch ! I want to make a chapter specifically about display and debug, but until then, this is an improvement for sure. Thanks!

[steveklabnik]

@bors: r+ rollup

[bors]

📌 Commit baef132 has been approved by steveklabnik

[sfackler]

This should be "lets", not "let's", right?

[steveklabnik]

ah yes, and it probably should be to std, not core.

@swaroopch , up for a second PR after this one lands? heh. It's already being tested in the rollup, or i'd say fix it first

[swaroopch]

@sfackler @steveklabnik I added a second commit to same branch in my fork - f6e5369 - but I'm a bit confused on how this works - should I do a separate PR?

[steveklabnik]

Ah! so, #25377 failed. so no, you don't need to make a new PR

[steveklabnik]

@bors: r+ rollup

[bors]

📌 Commit f6e5369 has been approved by steveklabnik