Add Sharpe to DeFi trackers

[rishabhng]

Adds Sharpe to the General tracker list.

This README is mostly organized as raw tracker URLs rather than annotated descriptions, so the change follows that existing format and adds only the canonical Sharpe site URL. Sharpe fits the General tracker section as a DeFi and crypto market intelligence dashboard covering DEX flow, stablecoins, narratives, derivatives positioning, listings, and news.

Website URL: https://www.sharpe.ai
Validation: git diff --check passes.
Linear: SHA-161

Disclosure: I work on Sharpe.

[rishabhng]

Following up on this DeFi trackers addition. Sharpe is a fit as a tracker/analytics terminal for DeFi market conditions, including arbitrage, derivatives/funding context, stablecoin views, and token-risk checks.

I can tighten the entry if you want it framed only as analytics rather than a broader terminal.