Rollup merge of #115752 - GuillaumeGomez:aliased-type-title, r=notriddle

rustdoc: Add missing "Aliased type" title in the sidebar

Follow-up of rust-lang/rust#115682.

The sections title are supposed to be present in the sidebar, we forgot to put this one so I added it into it. I also added the missing newly created `aliased-type` ID into the `DEFAULT_ID_MAP`.

r? `@notriddle`

Author: matthiaskrgr