Improve Documentation for Attendee List Generation Scripts.

[HarshKapadia2]

• The https://github.com/OurTechCommunity/catchup/blob/main/util/README.md file documents the usage of the two scripts https://github.com/OurTechCommunity/catchup/blob/main/util/create-attendee-handle-map.js and https://github.com/OurTechCommunity/catchup/blob/main/util/map-handles-to-catchup-attendees.js that aid in generating the attendees.adoc file for every session in summary/sessions.
• The issue is that the util/README.md document isn't very explicit in mentioning
  • What feature the two scripts are meant for (the Attendee List Generation feature).
  • The order of running the scripts.
  • From where (which directory) the scripts have to be run from.
• Adding this to the documentation would make it easier to use the Attendee List Generation feature.

Cc: @tusharnankani