Next.js datasets

Usage

- from: spice.ai/spice/nextjs/docs
  name: nextjs.docs

- from: spice.ai/spice/nextjs/issues
  name: nextjs.issues

- from: spice.ai/spice/nextjs/docs
  name: nextjs.docs

- from: spice.ai/spice/nextjs/issues
  name: nextjs.issues

Contributors ewgenius](https://github.com/ewgenius) sgrebnov](https://github.com/sgrebnov)