Stabilize `custom_code_classes_in_docs` feature

2 files changed, 38 insertions, 44 deletions

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index bdb55de8d63..39f24a13143 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -624,47 +624,3 @@ add the `--scrape-tests` flag.
 
 This flag enables the generation of links in the source code pages which allow the reader
 to jump to a type definition.
-
-### Custom CSS classes for code blocks
-
-```rust
-#![feature(custom_code_classes_in_docs)]
-
-/// ```custom,{class=language-c}
-/// int main(void) { return 0; }
-/// ```
-pub struct Bar;
-```
-
-The text `int main(void) { return 0; }` is rendered without highlighting in a code block
-with the class `language-c`. This can be used to highlight other languages through JavaScript
-libraries for example.
-
-Without the `custom` attribute, it would be generated as a Rust code example with an additional
-`language-C` CSS class. Therefore, if you specifically don't want it to be a Rust code example,
-don't forget to add the `custom` attribute.
-
-To be noted that you can replace `class=` with `.` to achieve the same result:
-
-```rust
-#![feature(custom_code_classes_in_docs)]
-
-/// ```custom,{.language-c}
-/// int main(void) { return 0; }
-/// ```
-pub struct Bar;
-```
-
-To be noted, `rust` and `.rust`/`class=rust` have different effects: `rust` indicates that this is
-a Rust code block whereas the two others add a "rust" CSS class on the code block.
-
-You can also use double quotes:
-
-```rust
-#![feature(custom_code_classes_in_docs)]
-
-/// ```"not rust" {."hello everyone"}
-/// int main(void) { return 0; }
-/// ```
-pub struct Bar;
-```
diff --git a/src/doc/rustdoc/src/write-documentation/documentation-tests.md b/src/doc/rustdoc/src/write-documentation/documentation-tests.md
index a7d3186fb78..9526f33359e 100644
--- a/src/doc/rustdoc/src/write-documentation/documentation-tests.md
+++ b/src/doc/rustdoc/src/write-documentation/documentation-tests.md
@@ -376,6 +376,44 @@ that the code sample should be compiled using the respective edition of Rust.
 # fn foo() {}
 ```
 
+### Custom CSS classes for code blocks
+
+```rust
+/// ```custom,{class=language-c}
+/// int main(void) { return 0; }
+/// ```
+pub struct Bar;
+```
+
+The text `int main(void) { return 0; }` is rendered without highlighting in a code block
+with the class `language-c`. This can be used to highlight other languages through JavaScript
+libraries for example.
+
+Without the `custom` attribute, it would be generated as a Rust code example with an additional
+`language-C` CSS class. Therefore, if you specifically don't want it to be a Rust code example,
+don't forget to add the `custom` attribute.
+
+To be noted that you can replace `class=` with `.` to achieve the same result:
+
+```rust
+/// ```custom,{.language-c}
+/// int main(void) { return 0; }
+/// ```
+pub struct Bar;
+```
+
+To be noted, `rust` and `.rust`/`class=rust` have different effects: `rust` indicates that this is
+a Rust code block whereas the two others add a "rust" CSS class on the code block.
+
+You can also use double quotes:
+
+```rust
+/// ```"not rust" {."hello everyone"}
+/// int main(void) { return 0; }
+/// ```
+pub struct Bar;
+```
+
 ## Syntax reference
 
 The *exact* syntax for code blocks, including the edge cases, can be found