Auto merge of rust-lang#108537 - GuillaumeGomez:rustdoc-search-whitespace-as-separator, r=notriddle

rustdoc: Allow whitespace as path separator like double colon

Fixes rust-lang#108447.

I think it makes sense since it allows more common cases, however it also makes the syntax heavier. Not sure what the rest of the team thinks about it. In any case we'll need to go through FCP.

Full explanation for the changes is available [here](rust-lang#108537 (comment)).

r? `@notriddle`

Author: bors

src/doc/rustdoc/src/how-to-read-rustdoc.md

@@ -110,6 +110,11 @@ Function signature searches also support arrays and slices. The explicit name
 or array of bytes, while square brackets `[u8]` will match either one. Empty
 square brackets, `[]`, will match any slice regardless of what it contains.
 
+Paths are supported as well, you can look for `Vec::new` or `Option::Some` or
+even `module::module_child::another_child::struct::field`. Whitespace characters
+are considered the same as `::`, so if you write `Vec    new`, it will be
+considered the same as `Vec::new`.
+
 ### Shortcuts
 
 Pressing `S` while focused elsewhere on the page will move focus to the