doc: the content has since been moved to the guide

Author: tshepang

src/README.md

@@ -5,10 +5,7 @@ This directory contains the source code of the rust project, including:
 
 For more information on how various parts of the compiler work, see the [rustc guide].
 
-There is also useful content in the following READMEs, which are gradually being moved over to the guide:
-- https://github.com/rust-lang/rust/tree/master/src/librustc/ty/query
-- https://github.com/rust-lang/rust/tree/master/src/librustc/dep_graph
-- https://github.com/rust-lang/rust/tree/master/src/librustc/infer/higher_ranked
-- https://github.com/rust-lang/rust/tree/master/src/librustc/infer/lexical_region_resolve
+There is also useful content in this README:
+https://github.com/rust-lang/rust/tree/master/src/librustc/infer/lexical_region_resolve.
 
 [rustc guide]: https://rust-lang.github.io/rustc-guide/about-this-guide.html