Update lib.rs (#6)

`destination` should be declared as `mut` in order to receiver lamports from `account`.

programs/9-closing-accounts/recommended/src/lib.rs

@@ -15,6 +15,7 @@ pub mod closing_accounts_recommended {
 pub struct Close<'info> {
     #[account(mut, close = destination)]
     account: Account<'info, Data>,
+    #[account(mut)]
     destination: AccountInfo<'info>,
 }