Update pull request template

[Matt Kane]

The PR template should match the one from netlify-plugin-gatsby

[Robert Churchill]

The PR template should match the one from netlify-plugin-gatsby

Is that a typo? This project is netlify-plugin-gatsby.

Perhaps meaning to match the templates here?

https://github.com/netlify/build-plugin-template/tree/master/.github

[Matt Kane]

Yeah, I meant netlify-plugin-nextjs