Point to check-cfg blog post.

Author: Mark-Simulacrum

posts/2024-07-25-Rust-1.80.0.md

@@ -86,6 +86,8 @@ The `[lints]` table in the `Cargo.toml` manifest can also be used to extend the
 unexpected_cfgs = { level = "warn", check-cfg = ['cfg(foo, values("bar"))'] }
 ```
 
+You can read more about this feature in a [previous blog post](https://blog.rust-lang.org/2024/05/06/check-cfg.html) announcing the availability of the feature on nightly.
+
 ### Exclusive ranges in patterns
 
 Rust ranged patterns can now use exclusive endpoints, written `a..b` or `..b` similar to the `Range` and `RangeTo` expression types. For example, the following patterns can now use the same constants for the end of one pattern and the start of the next: