Update create-app template for better parity with example app

Fixes #4613

Signed-off-by: Tim Hansen <timbonicus@gmail.com>

docs/features/software-catalog/installation.md

@@ -75,7 +75,7 @@ const app = createApp({
 You may also want to add a link to the catalog index page to your sidebar:
 
 ```tsx
-// packages/app/src/sidebar.tsx
+// packages/app/src/components/Root.tsx
 import HomeIcon from '@material-ui/icons/Home';
 
 // Somewhere within the <Sidebar>

docs/getting-started/configure-app-with-plugins.md

@@ -68,8 +68,8 @@ proxy:
 
 In a standard Backstage app created with
 [@backstage/create-app](./create-an-app.md), the sidebar is managed inside
-`packages/app/src/sidebar.tsx`. The file exports the entire `Sidebar` element of
-your app, which you can extend with additional entries by adding new
+`packages/app/src/components/Root.tsx`. The file exports the entire `Sidebar`
+element of your app, which you can extend with additional entries by adding new
 `SidebarItem` elements.
 
 For example, if you install the `api-docs` plugin, a matching `SidebarItem`

docs/tutorials/quickstart-app-plugin.md

@@ -49,7 +49,7 @@ title: Adding Custom Plugin to Existing Monorepo App
 
 Let's add a shortcut.
 
-1. Open and modify `root: packages > app > src > sidebar.tsx` with the
+1. Open and modify `root: packages > app > src > components > Root.tsx` with the
    following:
 
 ```tsx