Rollup merge of #119907 - asquared31415:fn_trait_docs, r=Nilstrieb

Update `fn()` trait implementation docs

Fixes #119903

This was FCP'd and approved for the 1.70.0 release, this is just a docs update to match that change.

library/core/src/primitive_docs.rs

@@ -1634,9 +1634,8 @@ mod prim_ref {}
 /// function pointers of varying length. Note that this is a convenience notation to avoid
 /// repetitive documentation, not valid Rust syntax.
 ///
-/// Due to a temporary restriction in Rust's type system, these traits are only implemented on
-/// functions that take 12 arguments or less, with the `"Rust"` and `"C"` ABIs. In the future, this
-/// may change:
+/// The following traits are implemented for function pointers with any number of arguments and
+/// any ABI.
 ///
 /// * [`PartialEq`]
 /// * [`Eq`]
@@ -1645,11 +1644,6 @@ mod prim_ref {}
 /// * [`Hash`]
 /// * [`Pointer`]
 /// * [`Debug`]
-///
-/// The following traits are implemented for function pointers with any number of arguments and
-/// any ABI. These traits have implementations that are automatically generated by the compiler,
-/// so are not limited by missing language features:
-///
 /// * [`Clone`]
 /// * [`Copy`]
 /// * [`Send`]