Adjust use of slack channels #security-questions and #security-team

Motivation:

The security-questions and security-team channels are not used in the way their titles and topics indicate they will be used.

Some people get notifications about security-questions, but those folks should probably set alerts to happen on security-team. The team should ideally make announcements in security-team. Discussion about releases and questions or notifying the team of problems with releases should also occur in security-team.

There is some agreement in the team on this proposal. (xjm, cilefen, mlhess provided feedback/review).

Below are some updated topics. We'll wait a bit for feedback on this proposal and then the security working group will decide how to move forward.

Current names / topics:

#security-questions
Security general conversation. Please don't discuss private issues by module name. Ask for help and a team member will followup. Please thread your discussions.

#security-team
Ask questions to the security team, however, remember not to discuss any issues or specific vulnerabilities. List of Team members: https://security.drupal.org/team-members

Proposed names / topics:

#security-team

Topic: Announcements, discussion of Security Advisories, and request to speak with team members. Monitored by: https://security.drupal.org/team-members Do not discuss private issues or vulnerabilities. General discussion: #security-discussion.

#security-discussion
Topic: Discussion of security questions in Drupal, sharing best practices. This channel is not actively monitored by the Security Team. Remember not to discuss private issues or vulnerabilities.