Rollup merge of #80659 - pierwill:edit-tokenstream, r=davidtwco
Rollup merge of #80659 - pierwill:edit-tokenstream, r=davidtwco

Edit rustc_ast::tokenstream docs

Fix some punctuation and wording, and add intra-documentation links.

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