Restore Next.js documentation

[unishigure]

Resolve #707

Restored the removed documentation for Next.js as docs/getting-started/nextjs.

[yusukebe]

I'm not super familiar with recent Next.js/Vercel things, but the link to https://vercel.com/docs/concepts/functions/edge-functions will redirect to https://vercel.com/docs/functions. I think they don't use "Edge Functions" anymore. If so, we have to change the description to follow the recent updates.

[unishigure]

As you pointed out, I reviewed the current version of Vercel Functions and found that it recommends migrating from Edge to Node.js. (ref)
Therefore, I removed references to Edge Functions and revised the content to focus on the Node.js runtime.
1344f37

[yusukebe]

@unishigure

Thank you for investigating. That's good.

So, should we update the starter template? This means removing this line:

https://github.com/honojs/starter/blob/5d6275be3eb9ad14f4e00bbadc572695e88ae18e/templates/nextjs/app/api/%5B...route%5D/route.ts#L4

[unishigure]

@yusukebe
Yes, that line is unnecessary.

I actually deleted that line and deployed to Vercel, and confirmed that it works without any issues.

[yusukebe]

@unishigure

Thanks! Removed honojs/starter#108

[yusukebe]

LGTM!

[yusukebe]

@unishigure

Looks good! I'll merge this now.

One thing, can you replay the comment? #738 (comment)

Thanks!