link the mentioned issue

Author: xxczaki

docs/CHANGELOG.md

@@ -5,7 +5,7 @@ Changelog
 
 ## v3.0.0-beta.5
 
-> NOTE: Since the previous beta version included serious issues, such as #749, they will now be deprecated. 
+> NOTE: Since the previous beta version included serious issues, such as [#749](https://github.com/node-fetch/node-fetch/issues/749), they will now be deprecated. 
 
 - Enhance: use built-in AbortSignal for typings.
 - Enhance: compile CJS modules as a seperate set of files.