docs: format with prettier (#1218)

docs/create-an-app.md

@@ -1,12 +1,16 @@
 # Backstage App
 
-To get set up quickly with your own Backstage project you can create a Backstage App.
+To get set up quickly with your own Backstage project you can create a Backstage
+App.
 
-A Backstage App is a monorepo setup with `lerna` that includes everything you need to run Backstage in your own environment.
+A Backstage App is a monorepo setup with `lerna` that includes everything you
+need to run Backstage in your own environment.
 
 ## Create an app
 
-To create a Backstage app, you will need to have [NodeJS](https://nodejs.org/en/download/) Active LTS Release installed (currently v12).
+To create a Backstage app, you will need to have
+[NodeJS](https://nodejs.org/en/download/) Active LTS Release installed
+(currently v12).
 
 With `npx`:
 
@@ -14,13 +18,15 @@ With `npx`:
 npx @backstage/cli create-app
 ```
 
-This will create a new Backstage App inside the current folder. The name of the app-folder is the name that was provided when prompted.
+This will create a new Backstage App inside the current folder. The name of the
+app-folder is the name that was provided when prompted.
 
 <p align='center'>
     <img src='https://github.com/spotify/backstage/raw/master/docs/create-app_output.png' width='600' alt='create app'>
 </p>
 
-Inside that directory, it will generate all the files and folder structure needed for you to run your app.
+Inside that directory, it will generate all the files and folder structure
+needed for you to run your app.
 
 ### Folder structure
 
@@ -69,4 +75,5 @@ cd my-backstage-app
 yarn start
 ```
 
-_When `yarn start` is ready it should open up a browser window displaying your app, if not you can navigate to `http://localhost:3000`._
+_When `yarn start` is ready it should open up a browser window displaying your
+app, if not you can navigate to `http://localhost:3000`._