Added installation screenshots.

Author: Steven Kirk

docs/getting-started/images/install-from-gallery.png

@@ -9,7 +9,6 @@ If you already have Visual Studio 2015 or higher installed, you can install the
 1. Visit the [GitHub for Visual Studio](https://visualstudio.github.com/) site.
 2. Click the **Download GitHub Extension for Visual Studio** button.
 3. In your computer's **Downloads** folder, double-click **GitHub.VisualStudio.vsix**.
-TODO: Insert screenshot
 4. In the pop-up window, click **Install**.
 5. After the installation is completed, run Visual Studio.
 
@@ -18,14 +17,16 @@ TODO: Insert screenshot
 If you're currently running Visual Studio 2015 or higher, you can install the extension from the Visual Studio gallery.
 
 1. In Visual Studio, open the **Tools** menu and click **Extensions and Updates**
+
 2. On the left side of the **Extensions and Updates** dialog, select **Online - Visual Studio gallery**
-TODO: Insert screenshot
+
 3. In the search box on the top right side, type **GitHub**
-TODO: Insert screenshot
+
 4. Select the **GitHub Extension for Visual Studio** entry and click **Download**
-TODO: Insert screenshot
+
+   ![image](images/install-from-gallery.png)
+
 5. After installation is completed, restart Visual Studio.
-TODO: Insert screenshot
 
 ## If you do not have Visual Studio installed yet
 
@@ -37,7 +38,7 @@ When you install Visual Studio, you can include the GitHub Extension for Visual
 
 1. Start the Visual Studio 2015 installer.
 2. Scroll down to **Common Tools** and check **GitHub Extension for Visual Studio**.
-TODO: Insert screenshot
+   ![image](images/vs2015-installer.png)
 3. Click the **Install** button.
 4. Once installation is complete, run Visual Studio 2015 and [update the extension](#updating-the-extension)
 
@@ -46,20 +47,25 @@ TODO: Insert screenshot
 **Note:** The Visual Studio 2017 installer is not guaranteed to install the latest version of the extension. Once the Visual Studio installation is complete, [update the extension](#updating-the-extension) from the Visual Studio gallery, or [run the installer](#installing-for-all-versions-of-visual-studio-2015-and-higher) from our website.
 
 1. Start the Visual Studio 2017 installer.
+
 2. Select the **Individual components** tab at the top.
-3. Scroll down to **Code tools** and check **GitHub Extension for Visual Studio**. TODO: Insert screenshot
+
+3. Scroll down to **Code tools** and check **GitHub Extension for Visual Studio**.
+
+   ![image](images/vs2017-installer.png)
+
 4. Click the **Modify** button.
+
 5. Once installation is complete, run Visual Studio 2017 and [update the extension](#updating-the-extension)
 
 ## Updating the extension
 
 **Note:** If you're currently running Visual Studio 2015 or higher and the extension is already installed, Visual Studio will check for and install updates automatically every 24 hours. For this update process to run, Visual Studio must not be running.
+
 Visual Studio 2017 will not run automatic updates until you update the extension at least once.
 
 1. In Visual Studio, open the **Tools** menu and click **Extensions and Updates**
 2. On the left side of the **Extensions and Updates** dialog, select **Updates - Visual Studio gallery**
-TODO: Insert screenshot
-4. If there are updates available, an entry titled **GitHub Extension for Visual Studio** will appear on the list. Select it and click **Update**
-TODO: Insert screenshot
-5. After installation is completed, restart Visual Studio.
-TODO: Insert screenshot
+3. If there are updates available, an entry titled **GitHub Extension for Visual Studio** will appear on the list. Select it and click **Update**
+   ![image](images/update-from-gallery.png)
+4. After installation is completed, restart Visual Studio.