Fix nits

Signed-off-by: xizheyin <[email protected]>

Author: xizheyin

src/rustc-driver/remarks-on-perma-unstable-features.md

@@ -1,8 +1,11 @@
-## Requirements for `rustc_private`
+
+# Remarks on perma unstable features
+
+## `rustc_private`
 
 ### Overview
 
-The `rustc-private` feature allows external crates to use compiler internals, but requires specific components to be properly installed. This document explains how to resolve common linker errors related to missing LLVM libraries when working with this feature.
+The `rustc_private` feature allows external crates to use compiler internals.
 
 ### Using `rustc-private` with Official Toolchains