rustdoc search should allow for 2 char symbols

[metajack]

How else should I find Eq?

[adrientetar]

drop as a keyword does not work either, I wonder why.

[adrientetar]

@metajack 2-char symbols work, e.g. me works; it's just that some particular keywords like eq or drop for instance are hitting #9981. I think that this issue should be closed as a dupe of it.

[lilyball]

Closed by #12195.