Remove stale reference to the test suite location

Author: albertlarsan68

src/README.md

@@ -1,8 +1,7 @@
-This directory contains the source code of the rust project, including:
+This directory contains some source code for the Rust project, including:
 
-- The test suite
 - The bootstrapping build system
-- Various submodules for tools, like cargo, etc.
+- Various submodules for tools, like cargo, tidy, etc.
 
 For more information on how various parts of the compiler work, see the [rustc dev guide].