Add descriptions

Write descriptions for the front matter of each new article.

docs/get-started/index.mdx

@@ -1,6 +1,7 @@
 ---
 id: index
 title: Getting started
+description: Get started with Avalonia. Install Avalonia and its prerequisites, then launch your first project using an Avalonia template.
 ---
 import DownloadAvaloniaRider from '/img/get-started/download-rider-avaloniarider.png';
 import DownloadAvaloniaExtensionForVS from '/img/get-started/download-vs-avalonia-extension.png';

docs/get-started/starter-tutorial/adding-a-control.md

@@ -1,6 +1,7 @@
 ---
 id: adding-a-control
 title: Adding a control
+description: How to add a button to your temperature converter app. Part 2 of 7 the Avalonia starter tutorial.
 ---
 
 import CalculateButtonLeft from '/img/get-started/calculate-button-left.png';

docs/get-started/starter-tutorial/adding-some-layout.md

@@ -1,6 +1,7 @@
 ---
 id: adding-some-layout
 title: Adding some layout
+description: How to use layout controls to have multiple controls on your temperature converter app. Part 3 of 7 the Avalonia starter tutorial.
 ---
 
 import TemperatureConverterTextOnly from '/img/get-started/temperature-converter-text-only.png';

docs/get-started/starter-tutorial/converting-data.md

@@ -1,6 +1,7 @@
 ---
 id: converting-data
 title: Converting data
+description: How to use code-behind to execute a response when the button is clicked. Part 6 of 7 the Avalonia starter tutorial.
 ---
 
 # Converting data

docs/get-started/starter-tutorial/customizing-the-avalonia-window.md

@@ -1,6 +1,7 @@
 ---
 id: customizing-the-avalonia-window
 title: Customizing the Avalonia window
+description: How to adjust the attributes of the Avalonia window. Part 4 of 7 the Avalonia starter tutorial.
 ---
 
 import AvaloniaWindowLayout from '/img/get-started/avalonia-window-layout.png';

docs/get-started/starter-tutorial/establishing-events-and-responses.mdx

@@ -1,6 +1,7 @@
 ---
 id: establishing-events-and-responses
 title: Establishing events and responses
+description: How to create an event handler to detect when the button is being clicked. Part 5 of 7 the Avalonia starter tutorial.
 ---
 
 import MainWindowCodeBehindLocation from '/img/get-started/mainwindow-codebehind-location.png';

docs/get-started/starter-tutorial/exercises.mdx

@@ -1,6 +1,7 @@
 ---
 id: exercises
 title: Exercises
+description: Test your knowledge of Avalonia on three coding exercises. Part 7 of 7 the Avalonia starter tutorial.
 ---
 
 # Starter exercises

docs/get-started/starter-tutorial/index.md

@@ -1,6 +1,7 @@
 ---
 id: index
 title: Starter tutorial
+description: Learn the basics of Avalonia by building a temperature converter app. Part 1 of 7 the Avalonia starter tutorial.
 ---
 
 import DocCardList from '@theme/DocCardList';

docs/get-started/xaml-previewers.mdx

@@ -1,6 +1,7 @@
 ---
 id: xaml-previewers
 title: XAML previewers
+description: How to use XAML previewers when developing with Avalonia in a supported IDE.
 ---
 
 import RiderXamlPreviewer from '/img/get-started/rider-xaml-previewer.png';