Add Prettier config to app

[nickserv]

Rationale

This monorepo has a Prettier config that affects formatting of all files, including the official templates. However, because this config isn't included in the templates, running Prettier (as recommended in the docs) will change the formatting of the app, which can be confusing or inconvenient.

Changes

Modified the init script to copy the monorepo's Prettier config to package.json (for any template). In the future we may want to make this extensible if third party templates need to set their own Prettier configs.

Testing

Created an example app with yarn create-react-app my-app, confirming that the Prettier config was created in package.json and running Prettier does not reformat the files (as the formatting is already correct).

[stale]

This pull request has been automatically marked as stale because it has not had any recent activity. It will be closed in 5 days if no further activity occurs.

[nickserv]

This is still an issue.

[nickserv]

There haven't been any conflicts. Is there anything I need to do to get this to a mergeable or reviewable state?

[stale]

This pull request has been automatically marked as stale because it has not had any recent activity. It will be closed in 5 days if no further activity occurs.

[nickserv]

This pull request is still working and awaiting review.

[nickserv]

This is what I would recommend to beginners of React and Prettier now, though I'd like opinions before committing it:

Suggested change

	arrowParens: 'avoid',
	singleQuote: true,
	semi: false,
	trailingComma: 'all',

Rationale

Option	Notes
arrowParens	Prettier now sets this on by default, as it makes it easier to add parameters and types, which is especially helpful for beginners
singleQuote	Prettier still uses double quotes for JSX, so it makes more sense to be consistent with the defaults
semi	Getting rid of semicolons makes it easier to read, write, and reorder lines of code, and Prettier already fixes the issues with ASI
trailingComma	Historically Prettier defaulted to ES5, but we use use Babel, so we can use newer syntax without worrying about browser support

[nickserv]

I've published prettier-config-nick if anyone would like to use it before this is merged.