docs: update code review docs to clarify fork PR security limitation

- Added clear note in Limitations section that PRs from forks are not supported
- Mentioned security concerns as the reason for this limitation
- Clarified that only same-repository branch PRs can be automatically reviewed

Author: emilieschario

apps/kilocode-docs/docs/advanced-usage/code-reviews.md

@@ -159,4 +159,5 @@ The Review Agent is ideal for:
 - The agent reviews **only the changed files**, not the entire repository.
 - Some highly dynamic or domain-specific code may require additional context in custom instructions.
 - The agent will only run on **selected repositories**.
+- **PRs from forks are not supported**. Only pull requests from branches within the same repository can be automatically reviewed.
 - During beta, review capacity may be throttled for extremely large PRs.