Add a `.gitignore` to examples missing it.

Many examples don’t currently include a .gitignore, which is fine when using create-next-app, but it will cause the example to not have it by other means, like a manual download or using the deploy to Vercel button.

The .gitignore file should look like this:

# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.

# dependencies
/node_modules

# testing
/coverage

# Next.js
/.next/
/out/

# production
/build

# misc
.DS_Store

# debug
npm-debug.log*
yarn-debug.log*
yarn-error.log*

# local env files
.env.local
.env.development.local
.env.test.local
.env.production.local

# Vercel
.vercel

If the example has other files that need to be ignored, feel free to add them. And if the example already has a .gitignore that’s not ignoring the files listed above, updates to it are also welcome!

[Timer]

Every single example needs the .gitignore added or merged with its existing one! A script should probably be wrote that automates this and checked into the PR, since we’ll want to update the default ignore list in the future.

[tanmaylaud]

Hi I have an open PR for this issue