Change HTTP Links to HTTPS in SUPPORT.md

Similar to issue #16167 and PR #16173
Change links to `The Atom Flight Manual` and `Atom Slack team` to support SSL/TLS by changing URL to `https://`
[ci skip]

Signed-off-by: U8N WXD <cs.temporary@icloud.com>

SUPPORT.md

@@ -2,10 +2,10 @@

If you're looking for support for Atom there are a lot of options, check out:

* User Documentation — [The Atom Flight Manual](http://flight-manual.atom.io)
* User Documentation — [The Atom Flight Manual](https://flight-manual.atom.io)
* Developer Documentation — [Atom API Documentation](https://atom.io/docs/api/latest)
* FAQ — [The Atom FAQ on Discuss](https://discuss.atom.io/c/faq)
* Message Board — [Discuss, the official Atom and Electron message board](https://discuss.atom.io)
* Chat — [Join the Atom Slack team](http://atom-slack.herokuapp.com/)
* Chat — [Join the Atom Slack team](https://atom-slack.herokuapp.com/)

On Discuss and in the Atom Slack team, there are a bunch of helpful community members that should be willing to point you in the right direction.