update pr-review doc

sdk/guides/github-workflows/pr-review.mdx

@@ -7,7 +7,9 @@ description: Use OpenHands Agent to generate meaningful pull request review
 This example is available on GitHub: [examples/03_github_workflows/02_pr_review/](https://github.com/OpenHands/software-agent-sdk/tree/main/examples/03_github_workflows/02_pr_review)
 </Note>
 
-Automatically review pull requests when labeled with `review-this`, providing feedback on code quality, security, and best practices.
+Automatically review pull requests, providing feedback on code quality, security, and best practices. Reviews can be triggered in two ways:
+- Requesting `openhands-agent` as a reviewer
+- Adding the `review-this` label to the PR
 
 ```yaml icon="yaml" expandable agent-sdk/examples/03_github_workflows/01_basic_action/workflow.yml
 
@@ -22,16 +24,22 @@ cp examples/03_github_workflows/02_pr_review/workflow.yml .github/workflows/pr-r
 # 2. Configure secrets in GitHub Settings → Secrets
 # Add: LLM_API_KEY
 
-# 3. Create a "review-this" label in your repository
+# 3. (Optional) Create a "review-this" label in your repository
 # Go to Issues → Labels → New label
+# You can also trigger reviews by requesting "openhands-agent" as a reviewer
 ```
 
 ## Features
 
-- **Automatic Trigger** - Reviews start when `review-this` label is added and is posted on the PR in only 2 or 3 minutes
+- **Fast Reviews** - Results posted on the PR in only 2 or 3 minutes
 - **Comprehensive Analysis** - Analyzes the changes given the repository context. Covers code quality, security, best practices
 - **GitHub Integration** - Posts comments directly to the PR
 
+## Security 
+
+- Users with write access (maintainers) can trigger reviews by requesting `openhands-agent` as a reviewer or adding the `review-this` label.
+- Maintainers need to read the PR to make sure it's safe to run.
+
 ## Related Files
 
 - [Agent Script](https://github.com/OpenHands/software-agent-sdk/blob/main/examples/03_github_workflows/02_pr_review/agent_script.py)