[MFSNW26] Updates root README description

[tonyqiu123]

Notion ticket link

Ticket Name

Implementation description

• Updated root README description: replaced generic placeholder with MFSN project overview (fullstack Svelte + Express + Postgres app, nonprofit mission, farm-to-school focus).
• Added Tony Qiu to Authors section with Instagram link.

Steps to test

1. Open the root README.md on this branch (locally or on GitHub).
2. Confirm the Description section shows the MFSN project summary and the Authors section includes Tony Qiu with the correct link.

What should reviewers focus on?

• Accuracy and tone of the project description.
• Whether the author entry and link are correct.

Checklist

• My PR name is descriptive and in imperative tense
• My commit messages are descriptive and in imperative tense. My commits are atomic and trivial commits are squashed or fixup'd into non-trivial commits
• I have run the appropriate linter(s)
• I have requested a review from the PL, as well as other devs who have background knowledge on this PR or who will be building on top of this PR

[fiona-cai]

LGTM!