Proposal: create an Istio Community Group

As other projects have dedicated community groups on community.cncf.io (list [here](https://community.cncf.io/chapters/)), I believe Istio can benefit tremendously in having a community home as well to host meetings, share them broadly within the CNCF community and beyond, and for more reasons (use of CNCF YouTube channels/playlist, hosting in an easy-to-access calendar and so on). As a meetup organiser and CNCF Ambassador I'd be happy to spearhead this and help organise and setup a calendar of events (releases where we interview the release team, special events, end-users stories). The[ Istio Office Hours proposal](https://docs.google.com/document/d/13voR8qZwG8lKI2_xtvYhN6msBHp0MAdvlDXMUqQGFEM/edit) can also fall/be run on community.cncf.io.

cc @linsun @craigbox @kfaseela

Start by reviewing the community.cncf.io chapters list and the linked Istio Office Hours proposal. Confirm the CNCF and Istio coordination needed for a community group, then define the calendar, meeting format, and event ownership. Done means the group is established with an accessible event calendar and an agreed plan for hosting meetings.

Written by the indexing model from the issue text.