Change name of the description filed to agenda field and add another field for user input

Requirement: Change name of the description filed to agenda field and add another field for user input

**Description Field Changes**
- Change the name of description field to agenda field and default text to the pre-defined agenda for the data plane informational meeting.

- Here is the anchor link to the agenda on the wiki page that describes the meeting - [link to agenda](https://dev.azure.com/azure-sdk/internal/_wiki/wikis/internal.wiki/663/Data-Plane-Informational-Meeting?anchor=what-to-expect-during-the-informational)

- This should be display field no input by user.

**New Additional Topics field**

- Add new field that "Additional Topics" that the service team member can use to add any additional topics or questions they wish to be addressed in the data plane informational meeting. Hover text or ? text should state "Use this field to indicate additional topics or questions you wish to be addressed in the data plane informational meeting."

The issue names no files, tests, or entry points. Start by locating the existing description field and its form, then verify the renamed agenda display field, its predefined meeting text and wiki link, and the new Additional Topics input with the specified hover text. Done means both fields appear with the requested behavior and wording.

Written by the indexing model from the issue text.