Rollup merge of #80457 - camelid:pretty-docs-commas, r=jonas-schievink
Rollup merge of #80457 - camelid:pretty-docs-commas, r=jonas-schievink

Add missing commas to `rustc_ast_pretty::pp` docs

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