docs: Fix missing closing code block ``` (#10424)

automerge

docs/src/implemented-proposals/cross-program-invocation.md

@@ -89,6 +89,7 @@ To sign an account with program derived addresses, a program may `invoke_signed(
             &[&["First addresses seed"], 
               &["Second addresses first seed", "Second addresses second seed"]],
         )?;
+```
 
 ### Reentrancy