[clang-tools-extra] [clang-tidy] Improve documentation of bugprone-pointer-arithmetic-on-polymorphic-object (PR #108324)

[Nicolas van Kempen via cfe-commits]

================
@@ -19,20 +19,35 @@ Example:
 .. code-block:: c++
 
   struct Base {
-    virtual void ~Base();
+    virtual ~Base();
+    int i;
   };
-
+  
   struct Derived : public Base {};
-
-  void foo() {
-    Base *b = new Derived[10];
-
+  
+  // Function that takes a pointer and performs pointer arithmetic
+  void foo(Base* b) {
     b += 1;
     // warning: pointer arithmetic on class that declares a virtual function can
     // result in undefined behavior if the dynamic type differs from the
     // pointer type
+  }
+  
+  void bar() {
+    Derived d[10];  // Array of derived objects
+    foo(d);         // Passing Derived pointer to foo(), which performs arithmetic
+  }
 
-    delete[] static_cast<Derived*>(b);
+  // Another example showing array access with polymorphic objects.
----------------
nicovank wrote:

```suggestion
```

https://github.com/llvm/llvm-project/pull/108324