Correct flawed URL to avoid a HTTP 404.

CONTRIBUTING.md

@@ -12,7 +12,7 @@ Resources to understand and help navigate the project include:
 
 ## Submitting improvements and corrections
 
-Please send a [GitHub Pull Request to Sekura](https://github.com/monero-project/sekura/pull/new/master/) with a clear list of what you've done (read more about [pull requests](http://help.github.com/pull-requests/)). Please follow coding conventions (below) and ensure all commits are atomic (one feature per commit.)
+Please send a [GitHub Pull Request to Sekura](https://github.com/monero-project/sekura/pull/new/master/) with a clear list of what you've done (read more about [pull requests](https://help.github.com/articles/about-pull-requests/)). Please follow coding conventions (below) and ensure all commits are atomic (one feature per commit.)
 
 Always write a clear log message for your commits. One line messages are fine for small changes, but bigger changes should look like this: