add internals link

Author: pietroalbini

posts/inside-rust/2020-08-24-1.46.0-prerelease.md

@@ -14,6 +14,8 @@ 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/2020-08-24/index.html>.
+The index is <https://dev-static.rust-lang.org/dist/2020-08-24/index.html>. You
+can leave feedback on the [internals thread][internals].
 
 [relnotes]: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1460-2020-08-27
+[internals]: https://internals.rust-lang.org/t/rust-1-46-0-pre-release-testing/12957