Add ICS fille for the Microsoft Agent Framework Community Call

[lukemurraynz]

Add an ICS file (Calendar appointment) for the Microsoft Agent Framework Community Call

The Calendar Appointments help people add to their calendar, as a reminder to join, and the calendar also makes sure any timezone issues are adjusted, so they appear in local time without people having to guess the time/date in their local time.

https://github.com/microsoft/agent-framework/blob/main/COMMUNITY.md