Add Reddit, Bluesky, and Mastodon to Collaboration page

[cybette]

• Mastodon https://mastodon.social/@InstructLab
• Bluesky https://bsky.app/profile/instructlab.bsky.social
• Reddit https://reddit.com/r/instructlab

The channels have been set up (#216) and we need to add them to the Collaboration page for awareness as we get more active in these channels.

[github-actions]

This issue has been automatically marked as stale because it has not had activity within 90 days. It will be automatically closed if no further activity occurs within 30 days.

[marta-tomzik]

@mingxzhao I'm happy to do it 👍

[cybette]

Thanks @marta-tomzik ! Please note that the Bluesky channel is not currently active, so if you add it please mention that.

For Reddit, please encourage people to submit articles to the InstructLab subreddit.

[marta-tomzik]

I've submitted the PR to this issue 👍