Foundations/Join the Odin Community - add guideline to observe before jumping in

[JustWaveThings]

Because

• Gives guidance that can help new learners integrate better into the server.

This PR

• Adds Discord guideline:

• Take some time to observe the server before jumping in: This helps you understand how our community interacts and communicates.

Issue

n/a

Additional Information

https://discord.com/channels/505093832157691914/1313787229608611852/1313952034361311253

Pull Request Requirements

• I have thoroughly read and understand The Odin Project curriculum contributing guide
• The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
• If this PR addresses an open issue, it is linked in the Issue section
• If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• If any lesson files are included in this PR, they follow the Layout Style Guide