[Docs Agent] Bug fix: Prevent the AQA model from failing when a response returns entries containing a null string

[kyolee415]

Description of the change

• Prevent the AQA model from failing when its response's metadata returns entries containing an empty string.
• Update the DraftReleaseNotes tasks with polished prompts.
• Add a task file example to the main README.md file.
• Minor update in the ExtractWorkflows task to remove extra spaces.

Motivation

Bug fix mainly

Type of change

Choose one: (Bug fix)

Checklist

• [ X] I have performed a self-review of my code.
• [ X] I have added detailed comments to my code where applicable.
• [ X] I have verified that my change does not break existing code.
• [ X] My PR is based on the latest changes of the main branch (if unsure, please run git pull --rebase upstream main).
• [ X] I am familiar with the Google Style Guide for the language I have coded in.
• [ X] I have read through the Contributing Guide and signed the Contributor License Agreement.