servo: Merge #15511 - Fix fmt::Display vs fmt::Debug URL (from r3c0d3x:patch-1); r=Wafflespeanut

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Fixed a Rust documentation link in [`HACKING_QUICKSTART.md`](44e808b5cf/docs/HACKING_QUICKSTART.md)
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The link to Rust's documentation comparing `fmt::Display` and `fmt::Debug` no longer points to the right section of the page.

- [x] These changes do not require tests because it's simply changing a URL in the documentation.

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Source-Repo: https://github.com/servo/servo
Source-Revision: eca8c4ed7384e98efcb15b8ef603f27650126fd5

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 9451958c39f58bfc06666554d45dda1fa6b7d381

servo/docs/HACKING_QUICKSTART.md

@@ -177,7 +177,7 @@ Use `RUST_BACKTRACE=1` to dump the backtrace when Servo panics.
 
 ### println!()
 
-You will want to add your own logs. Luckily, many structures [implement the `fmt::Debug` trait](https://doc.rust-lang.org/std/fmt/#fmt::display-vs-fmt::debug), so adding:
+You will want to add your own logs. Luckily, many structures [implement the `fmt::Debug` trait](https://doc.rust-lang.org/std/fmt/#fmtdisplay-vs-fmtdebug), so adding:
 
 ``` rust
 println!("foobar: {:?}", foobar)