Asynchronous Code: add to "Additional Resources"

[SpoonOil]

Because

Just provides some more info on promises and some context for their syntax via an article.

This PR

• In Additional Resources I added the article with a small blurb summarizing it.

Issue

Closes #XXXXX

Additional Information

Pull Request Requirements

• [x] I have thoroughly read and understand The Odin Project curriculum contributing guide
• [x] 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
• [x] The Because section summarizes the reason for this PR
• [x] The This PR section has a bullet point list describing the changes in this PR
• [x] If this PR addresses an open issue, it is linked in the Issue section
• [x] If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• [x] If any lesson files are included in this PR, they follow the Layout Style Guide

[bycdiaz]

@SpoonOil Does the resource you're proposing to add have context that our lesson lacks? I'd love to understand the motivation for the proposal.

[bycdiaz]

@SpoonOil Just checking in. Let me know if you are able to look into the question I posed. If not, I'll close this PR for now.

[bycdiaz]

@SpoonOil I'm going to close this ticket for now. Let us know if you'd like to revisit this in the future.