docs: clarify the Lambda ARN CfnOutput description

[timpugh]

Smallest-possible PR to exercise the pull-request-only CI paths that direct pushes to main skip:

• pr-title workflow — validates this title's Conventional-Commits prefix.
• cdk-diff job — synthesizes base vs PR and posts the CloudFormation diff as a sticky comment. This change tweaks one CfnOutput description, so the diff should be a single Outputs-only line (a clean, non-empty render to confirm the job works).
• oasdiff breaking-change gate (in the test job) — no docs/openapi.json change here, so it should report no breaking changes (confirms the gate doesn't false-positive on a normal PR).
• plus the usual quality / test / cdk-check jobs.

Functional change: none — only the wording of the FunctionArnOutput description. Safe to merge or close once CI is observed.

🤖 Generated with Claude Code

[github-actions]

🏗️ CDK infra diff — PR vs main

ServerlessApp-us-east-1-stage/ServerlessAppBackend-us-east-1

Stack ServerlessApp-us-east-1-stage/ServerlessAppBackend-us-east-1 (ServerlessAppBackend-us-east-1)
Outputs
[~] Output ServerlessAppBackend-us-east-1/FunctionArnOutput FunctionArnOutput: {"Description":"Serverless App Lambda Function ARN","Value":{"Fn::GetAtt":["AppApiFunctionDE515850","Arn"]}} to {"Description":"ARN of the Lambda function backing the greeting API","Value":{"Fn::GetAtt":["AppApiFunctionDE515850","Arn"]}}



✨  Number of stacks with differences: 1