Fix rustdoc highlighting of `&` and `*`.
Fix rustdoc highlighting of `&` and `*`.

Whitespace tokens were included, so the span check used with `&` was
incorrect, and it was never highlighted as kw-2.

The `*` in `*foo` and `*const T` should also be highlighted kw-2, so I
added them. Note that this *will* cause mishighlighting of code like
`1*2`, but that should have been written `1 * 2`. Same deal with `1&2`.

graydon/rust,graydon/rust,GBGamer/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust