fix: init renames _prettierrc.js to .prettierrc.js

In facebook/react-native@65eea9d, the prettier config for ESLint has been extracted to a .prettierrc file.

It was however not added to the React Native `template` folder and this was causing linting issues in newly generated RN apps.

In that [PR](facebook/react-native#25478) to `react-native`, a `_prettierrc.js` file was added to the `template` folder, however, a newly generated project would have the file still underscored (see facebook/react-native#25478 (comment))

This commit addresses that issue by adding `prettierrc.js` to the list of underscored files that need to be renamed to dotfiles.

packages/cli/src/commands/init/editTemplate.js

@@ -48,6 +48,7 @@ const UNDERSCORED_DOTFILES = [
   'flowconfig',
   'gitattributes',
   'gitignore',
+  'prettierrc.js',
   'watchmanconfig',
 ];