We need to document new features and changes made to QuickSurveys as part of this epic in the public extension documentation.

AC:

• Update the capabilities and limitations list under the "Documentation and features" header.
• Update code examples to use new questions key in-place of the deprecated keys (it might be worth mentioning the old keys and telling the reader to avoid them).
• Add code example for multi-question surveys.
• Update infobox information such as authors and version number.
• Check existing documentation to make sure it's still relevant with the new schema changes and update it if needed.