generative-ai: Add anti pattern example

Author: corona10

getting-started/generative-ai.rst

@@ -24,3 +24,10 @@ Unacceptable uses
 Maintainers may close issues and PRs that are not useful or productive, including
 those that are fully generated by AI. If a contributor repeatedly opens unproductive
 issues or PRs, they may be blocked.
+
+Anti-patterns
+=============
+- While AI-assisted tools such as autocompletion can enhance productivity, they sometimes rewrite entire code blocks instead of making small, focused edits.
+  This can make it more difficult to review changes and to fully understand both the original intent of the code and the rationale behind the new modifications.
+  Please keep maintaining consistency with the original code helps preserve clarity, traceability, and meaningful review.
+