I wrote a [script](https://github.com/j0lv3r4/dependency-version-updater) to update dependencies recursively in `package.json` files, e.g.:
```
$ node index.js --path="./examples" --dependencies="react=^16.7.0,react-dom=^16.7.0"
```
This PR contains the result against the examples folder.
The `with-flow` sample has some obsolete definitions which are unused by the sample code. Removing the un-imported declarations is the easiest approach.
Changes:
* updated packages
* moved the content of `layout` to `_app.js` and created simple `Page` component
* replaced `import * as React` because it is not necessary to import everything
* moved `next.js.flow` to `flow-typed` as it is default directory for library definitions
* updated the gif
* Examples: clarify language around Yarn create & npx
* add missing READMEs and create-next-app usage
* suggest people tag jthegedus in firebase related issues
* add yarn alt instructions
* cerebraljs example readme & fixes
* remove global npm install of create-next-app
* add npx to create-next-app command in examples
* add bash to shell snippets
* add yarn create to next-app command in examples
* fix READMEs named with lowercase
* change READMEs to use UPPERCASE
