The tracking issue for this feature is: #50146

You can add alias(es) to an item when using the rustdoc search through the doc(alias) attribute. Example:

# #![allow(unused_variables)]
#![feature(doc_alias)]

#fn main() {
#[doc(alias = "x")]
#[doc(alias = "big")]
pub struct BigX;
#}

Then, when looking for it through the rustdoc search, if you enter "x" or "big", search will show the BigX struct first.

Note that this feature is currently hidden behind the feature(doc_alias) gate.