add descriptions to images in getting started section

Author: paladique

docs/getting-started/authenticating-to-github.md

@@ -10,10 +10,10 @@ Before you authenticate, you must already have a GitHub or GitHub Enterprise acc
 > **Note:** If your organization is on the [Business plan](https://help.github.com/articles/organization-billing-plans) and has enabled SAML single sign-on, you must create and authorize a personal access token to access protected content. For more information on creating personal access tokens, see "[Creating a personal access token for the command line](https://help.github.com/articles/creating-a-personal-access-token-for-the-command-line). For more information on authenticating with SAML single sign-on, see "[About authentication with SAML single sign-on](https://help.github.com/articles/about-authentication-with-saml-single-sign-on)."
 
 1. In Visual Studio, select **Team Explorer** from the **View** menu.
-![](images/view_team_explorer.png)
+![Team Explorer in the view menu](images/view_team_explorer.png)
 2. In the Team Explorer pane, click the **Manage Connections** toolbar button.
-![](images/manage_connections.png)
+![Manage connections toolbar button in the Team Explorer pane](images/manage_connections.png)
 3. Click the **Connect** link in the GitHub section. If you are already connected to a GitHub instance and want to connect to another, this link will not be visible; instead click **Manage Connections** and then **Connect to GitHub**.
-![](images/connect_to_github.png)
+![Connect to GitHub in the manage connections dropdown in the Team Explorer pane](images/connect_to_github.png)
 4. In the **Connect to GitHub dialog** choose **GitHub** or **GitHub Enterprise**, depending on which product you're using.
 5. Type your credentials, then click **Sign In**.

docs/getting-started/configuring-git-in-visual-studio.md

@@ -8,10 +8,10 @@ The name and email that will be displayed with your commits can be set from Team
 
 2. Click the **Settings** button in Team Explorer.
 
-   ![image](images/settings-button.png)
+   ![The settings button in Team Explorer pane](images/settings-button.png)
 
 3. Click **Global Settings** in the Team Explorer Settings page
 
-   ![image](images/global-settings-link.png)
+   ![The global settings button in the Team Explorer settings page](images/global-settings-link.png)
 
-4. Enter the name and email that you would like to appear in commits.
+4. Enter the name and email that you would like to appear in commits.

docs/getting-started/installing-github-for-visual-studio.md

@@ -24,7 +24,7 @@ If you're currently running Visual Studio 2015 or higher, you can install the ex
 
 4. Select the **GitHub Extension for Visual Studio** entry and click **Download**
 
-   ![image](images/install-from-gallery.png)
+   ![Installing GitHub for Visual Studio in the settings extensions and updates gallery](images/install-from-gallery.png)
 
 5. After installation is completed, restart Visual Studio.
 
@@ -38,7 +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**.
-   ![image](images/vs2015-installer.png)
+   ![GitHub Extension for Visual Studio in the common tools section of the Visual Studio 2015 installer](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)
 
@@ -52,7 +52,7 @@ When you install Visual Studio, you can include the GitHub Extension for Visual
 
 3. Scroll down to **Code tools** and check **GitHub Extension for Visual Studio**.
 
-   ![image](images/vs2017-installer.png)
+   ![GitHub Extension for Visual Studio in the code tools section of the Visual Studio 2017 installer](images/vs2017-installer.png)
 
 4. Click the **Modify** button.
 
@@ -67,5 +67,5 @@ Visual Studio 2017 will not run automatic updates until you update the extension
 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**
 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)
+   ![Updating GitHub for Visual Studio in the settings extensions and updates gallery](images/update-from-gallery.png)
 4. After installation is completed, restart Visual Studio.