Missing `Methods from Deref<Target={primitive}>` section in documentation for types in `#![no_std]` crates

[mitaa]

The links to as_ptr and chars on the collection crates page of String are broken.

This is because they refer to methods of str but link to the same page (String), relying on the Methods from Deref<Target=str> section which is missing for some reason (seems to apply to the entire collections crate).

[steveklabnik]

This is a duplicate of #32129

[ollie27]

This isn't a dupe of #32129. The issue here is the lack of the Methods from Deref<Target=str> section on the collections::string::String page which I believe is because it's a #![no_std] crate. So this needs to be reopened.

[MaloJaffre]

Here is a reduced testcase:

#![no_std]
pub struct DeStr;
impl core::ops::Deref for DeStr {
    type Target = str;
    fn deref(&self) -> &str {
        unimplemented!()
    }
}

[jyn514]

This looks like a duplicate of #73423.

[Nemo157]

no_std doesn't seem relevant, removing it from the reduced testcase still fails to add a "Mtehods from Deref<Target = str>" section (though it does create a broken link to it in the sidebar).