examples: Fix command key arguments

None of the arguments to this command are keys

Author: gavrie

examples/hello.rs

@@ -29,7 +29,7 @@ redis_module! {
     version: 1,
     data_types: [],
     commands: [
-        ["hello.mul", hello_mul, "", 1, 1, 1],
+        ["hello.mul", hello_mul, "", 0, 0, 0],
     ],
 }