cli: Add Limbo version back to shell

cli/main.rs

@@ -31,6 +31,8 @@ fn main() -> anyhow::Result<()> {
         }
         return Ok(());
     }
+    println!("Limbo v{}", env!("CARGO_PKG_VERSION"));
+    println!("Enter \".help\" for usage hints.");
     let mut rl = DefaultEditor::new()?;
     let home = dirs::home_dir().expect("Could not determine home directory");
     let history_file = home.join(".limbo_history");