Add test to ensure doc(primitive) is not recognized anymore

tests/ui/rustdoc/doc-primitive.rs

@@ -0,0 +1,8 @@
+#![deny(invalid_doc_attributes)]
+
+#[doc(primitive = "foo")]
+//~^ ERROR unknown `doc` attribute `primitive`
+//~| WARN
+mod bar {}
+
+fn main() {}

tests/ui/rustdoc/doc-primitive.stderr

@@ -0,0 +1,16 @@
+error: unknown `doc` attribute `primitive`
+  --> $DIR/doc-primitive.rs:3:7
+   |
+LL | #[doc(primitive = "foo")]
+   |       ^^^^^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #82730 <https://github.com/rust-lang/rust/issues/82730>
+note: the lint level is defined here
+  --> $DIR/doc-primitive.rs:1:9
+   |
+LL | #![deny(invalid_doc_attributes)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+