update relnotes link

Author: pietroalbini

posts/2021-05-06-Rust-1.52.0.md

@@ -21,7 +21,7 @@ from the appropriate page on our website, and check out the
 [detailed release notes for 1.52.0][notes] on GitHub.
 
 [install]: https://www.rust-lang.org/install.html
-[notes]: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1510-2021-03-25
+[notes]: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1520-2021-05-06
 
 ## What's in 1.52.0 stable