[Ecosystem Outreach] - Showcase - Indigo

[0xBora]

Checklist

• I have read the How to Contribute.
• I have read the Showcase Requirements
• I have run yarn build after adding my changes without getting any errors.
• I have not committed any changes to yarn.lock (or have removed these changes).

Showcase addition

    title: "Indigo",
    description:
      "Indigo is an autonomous synthetics protocol for on-chain price exposure to real-world assets, built on Cardano.",
    preview: require("./showcase/indigo.png"),
    website: "https://indigoprotocol.io/",
    source: "https://github.com/IndigoProtocol/indigo-smart-contracts",
    tags: ["marketplace", "opensource"],

Relevant to #1548

[rphair]

category tokenization (or equivalent) when ready 🎉