fix markdown

Co-authored-by: Philipp Krones <[email protected]>

Author: lolbinarycat

.github/ISSUE_TEMPLATE/new_lint.yml

@@ -60,7 +60,7 @@ body:
         You can also look through the list of [rustc's allowed-by-default lints][allowed-by-default],
         as those won't show up in the playground above.
 
-        [allowed-by-default](https://doc.rust-lang.org/rustc/lints/listing/allowed-by-default.html)
+        [allowed-by-default]: https://doc.rust-lang.org/rustc/lints/listing/allowed-by-default.html
 
         [playground]: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2024&code=%23%21%5Bwarn%28clippy%3A%3Apedantic%29%5D%0A%23%21%5Bwarn%28clippy%3A%3Anursery%29%5D%0A%23%21%5Bwarn%28clippy%3A%3Arestriction%29%5D%0A%23%21%5Bwarn%28clippy%3A%3Aall%29%5D%0A%23%21%5Ballow%28clippy%3A%3Ablanket_clippy_restriction_lints%2C+reason+%3D+%22testing+to+see+if+any+restriction+lints+match+given+code%22%29%5D%0A%0A%2F%2F%21+Template+that+can+be+used+to+see+what+clippy+lints+a+given+piece+of+code+would+trigger
       placeholder: Unlike `clippy::...`, the proposed lint would...