Make README notice larger.

Author: ehuss

README.md

@@ -3,7 +3,13 @@
 [![](https://vsmarketplacebadge.apphb.com/version/rust-lang.rust.svg)](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust)
 [![VSCode + Node.js CI](https://img.shields.io/github/workflow/status/rust-lang/rls-vscode/VSCode%20+%20Node.js%20CI.svg?logo=github)](https://github.com/rust-lang/rls-vscode/actions?query=workflow%3A%22VSCode+%2B+Node.js+CI%22)
 
-> Note: This extension has been deprecated in favor of the [rust-analyzer project](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust-analyzer).
+----
+
+> **Warning**
+> # This extension is no longer maintained.
+> This has been replaced by the [**rust-analyzer extension**](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust-analyzer).
+
+-----
 
 Adds language support for Rust to Visual Studio Code. Supports: