Update posts/inside-rust/2021-06-15-1.53.0-prelease.md

Co-authored-by: Mara Bos <[email protected]>

Author: pietroalbini

posts/inside-rust/2021-06-15-1.53.0-prelease.md

@@ -14,7 +14,7 @@ You can try it out locally by running:
 RUSTUP_DIST_SERVER=https://dev-static.rust-lang.org rustup update stable
 ```
 
-The index is <https://dev-static.rust-lang.org/dist/2021-05-04/index.html>. You
+The index is <https://dev-static.rust-lang.org/dist/2021-06-15/index.html>. You
 can leave feedback on the [internals thread][internals].
 
 [relnotes]: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1530-2021-06-17