Fix cut-&-pasto in example [2]

Co-authored-by: Sander de Smalen <[email protected]>

main/acle.md

@@ -4712,7 +4712,7 @@ architectural state differently. For example:
    void (*ptr2)() __arm_out("za");
    void (*ptr3)() __arm_inout("za");
    void (*ptr4)() __arm_preserves("za");
-   void (*ptr4)();
+   void (*ptr5)();
 
    void test() {
      ptr1 = f1;    // OK