docs(community): Add Bluesky follow link

[parksu0219]

Description

This PR updates the community.md documentation page to include a link to the official Lit project account on Bluesky (https://bsky.app/profile/lit.dev).

Motivation

To expand the reach of Lit updates and provide community members with an additional platform to follow the project's news and announcements.

Changes

• Added a new list item in the "Follow us..." section specifically for the Bluesky link.
• The existing link and description for X (formerly Twitter) have been retained.
• Ensured consistency in list item formatting and indentation.

Reviewer Checklist

• Verify the Bluesky URL is correct: https://bsky.app/profile/lit.dev
• Confirm that both the X (formerly Twitter) and Bluesky links are present in the rendered documentation.
• Check that the formatting and indentation of the new list item are consistent with others.
• Read through the added text for clarity and accuracy.

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