Add check-cfg blog post in the documentation

Author: Urgau

src/doc/src/reference/build-scripts.md

@@ -258,6 +258,8 @@ identifier, the value should be a string.
 
 ### `cargo::rustc-check-cfg=CHECK_CFG` {#rustc-check-cfg}
 
+*See the announcement [blog post][check-cfg-blog-post] for more a global view of the feature.*
+
 Add to the list of expected config names and values that is used when checking
 the _reachable_ cfg expressions.
 
@@ -290,6 +292,7 @@ if foo_bar_condition {
 }
 ```
 
+[check-cfg-blog-post]: https://blog.rust-lang.org/2024/05/06/check-cfg.html
 [option-check-cfg]: ../../rustc/command-line-arguments.md#option-check-cfg
 
 ### `cargo::rustc-env=VAR=VALUE` {#rustc-env}