Correct errsh links in config checks (#19280)
Correct errsh links in config checks (#19280)

This makes sure we're using `next.js` in the err.sh links instead of `nextjs` since that leads to a 404
flybayer/next.js,zeit/next.js,zeit/next.js,azukaru/next.js,JeromeFitz/next.js,flybayer/next.js,azukaru/next.js,flybayer/next.js,azukaru/next.js,JeromeFitz/next.js,flybayer/next.js,JeromeFitz/next.js,azukaru/next.js,JeromeFitz/next.js,zeit/next.js