Update lsp-rust.md (#2652)

Correct me if I'm wrong, but RLS is no longer the default, right?

Author: bjodah

docs/manual-language-docs/lsp-rust.md

@@ -2,7 +2,7 @@
 
 NOTE: If you are using `rustic-mode`, you have to change `rustic-lsp-server` instead of `lsp-rust-server`, since it also supports eglot as a lightweight alternative to lsp-mode.
 
-- `lsp-rust-server` Choose LSP server (default is RLS)
+- `lsp-rust-server` Choose LSP server (default is rust-analyzer)
 
 - `lsp-rust-switch-server` Switch priorities of lsp servers