Auto merge of #13937 - epage:docs, r=weihanglo

docs(ref): Simplify check-cfg build.rs docs

### What does this PR try to resolve?

After looking over the rust documentation updates, decided to look over Cargo's build.rs documentation.

- Removed link to the blog post as that is not evergreen documentation
- Collapsed down the example to put more emphasis on the more complete example

### How should we test and review this PR?

### Additional information

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

@@ -258,13 +258,11 @@ 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.
+the _reachable_ cfg expressions with the [`unexpected_cfgs`][unexpected-cfgs] lint.
 
-For details on the syntax of `CHECK_CFG`, see `rustc` [`--check-cfg` flag][option-check-cfg].
-See also the [`unexpected_cfgs`][unexpected-cfgs] lint.
+The syntax of `CHECK_CFG` mirrors the `rustc` [`--check-cfg` flag][option-check-cfg], see
+[Checking conditional configurations][checking-conditional-configurations] for more details.
 
 > Note: `cargo:rustc-check-cfg` (single-colon) can be used if your MSRV is below Rust 1.77
 
@@ -273,31 +271,23 @@ The instruction can be used like this:
 ```rust,no_run
 // build.rs
 println!("cargo::rustc-check-cfg=cfg(foo, values(\"bar\"))");
+if foo_bar_condition {
+    println!("cargo::rustc-cfg=foo=\"bar\"");
+}
 ```
 
 Note that all possible cfgs should be defined, regardless of which cfgs are
 currently enabled. This includes all possible values of a given cfg name.
 
 It is recommended to group the `cargo::rustc-check-cfg` and
 [`cargo::rustc-cfg`][option-cfg] instructions as closely as possible in order to
-avoid typos, missing check-cfg, stalled cfgs...
-
-#### Example of using `cargo::rustc-check-cfg` and `cargo::rustc-cfg` together
-
-```rust,no_run
-// build.rs
-println!("cargo::rustc-check-cfg=cfg(foo, values(\"bar\"))");
-if foo_bar_condition {
-    println!("cargo::rustc-cfg=foo=\"bar\"");
-}
-```
+avoid typos, missing check-cfg, stale cfgs...
 
-For a more complete example see in the [build script examples][build-script-examples] page
-the [conditional compilation][conditional-compilation-example] example.
+See also the
+[conditional compilation][conditional-compilation-example] example.
 
-[check-cfg-blog-post]: https://blog.rust-lang.org/2024/05/06/check-cfg.html
+[checking-conditional-configurations]: ../../rustc/check-cfg.html
 [option-check-cfg]: ../../rustc/command-line-arguments.md#option-check-cfg
-[build-script-examples]: build-script-examples.md
 [conditional-compilation-example]: build-script-examples.md#conditional-compilation
 
 ### `cargo::rustc-env=VAR=VALUE` {#rustc-env}