Revert "Remove private macros from documentation"

This reverts commit 033dc0123e.

This regression has been fixed:
https://github.com/rust-lang/rust/pull/88456

src/iter.rs

@@ -42,8 +42,6 @@ where
     }
 }
 
-// https://github.com/rust-lang/rust/issues/88453
-#[doc(hidden)]
 macro_rules! impl_next {
     ( $self:ident , $split_method:ident , $swap_fn:expr ) => {{
         $self

src/lib.rs

@@ -170,8 +170,6 @@ use std::path::Path;
 use std::path::PathBuf;
 use std::result;
 
-// https://github.com/rust-lang/rust/issues/88453
-#[doc(hidden)]
 macro_rules! if_raw_str {
     ( $($item:item)+ ) => {
         $(