Update README.md

Update README.md

Remove Google Group and Slack because users are NOT active enough on these two platforms.

Update README.md

Remove Google Group and Slack because users are NOT active enough on these two platforms.

Update README.md

Remove Google Group and Slack because users are NOT active enough on these two platforms.

Update README.md

Remove Google Group and Slack because users are NOT active enough on these two platforms.

Update README.md

Remove Google Group and Slack because users are NOT active enough on these two platforms.

Update README.md

Remove Google Group and Slack because users are NOT active enough on these two platforms.

Update README.md

Remove Google Group and Slack because users are NOT active enough on these two platforms.

Update README.md

Remove Google Group and Slack because users are NOT active enough on these two platforms.

Update README.md

Remove Google Group and Slack because users are NOT active enough on these two platforms.