Rollup merge of #70700 - jrvidal:include-macro-paths, r=Dylan-DPC
Rollup merge of #70700 - jrvidal:include-macro-paths, r=Dylan-DPC

Expand on platform details of `include_xxx` macros

This is a small detail that is not explicitly mentioned, but it left me scratching my head for a while until I looked into its implementation details. Maybe worth mentioning.

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