rustdoc: remove rust logo from non-Rust crates

compiler/rustc_errors/src/lib.rs

@@ -3,6 +3,8 @@
 //! This module contains the code for creating and emitting diagnostics.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![cfg_attr(not(bootstrap), doc(rust_logo))]
+#![cfg_attr(not(bootstrap), feature(rustdoc_internals))]
 #![feature(array_windows)]
 #![feature(extract_if)]
 #![feature(if_let_guard)]