Added new page to the guide intro page

Now it's listed along with the other reference designs.

Also fixed the border radius on one of the images.

_compress_images_cache.yml

@@ -2404,3 +2404,5 @@ assets/images/social-media/social-media.jpg: social-media.jpg
 assets/images/social-media/[email protected]: [email protected]
 assets/images/submit-header-design-preview.jpg: submit-header-design-preview.jpg
 assets/mstile-150x150.png: mstile-150x150.png
+assets/images/guide/multiple-wallets.png: multiple-wallets.png
+assets/images/guide/[email protected]: [email protected]

guide.md

@@ -141,7 +141,20 @@ Exploring the concept of progressive security, in which applications help users
 An overview and considerations for bitcoin wallets that are managed by multiple owners.
 
 </div>
-<div class="column -blank" markdown="1">
+<div class="column" markdown="1">
+
+{% include image.html
+   image = "/assets/images/guide/multiple-wallets.png"
+   retina = "/assets/images/guide/multiple-[email protected]"
+   alt-text = "Three mobile mock-ups of a user flow for managing multiple wallets in an application"
+   width = 400
+   height = 210
+   link-url = "/guide/multiple-wallets/"
+%}
+
+<h2 class="h3" markdown="1">[Multiple wallets]({{ '/guide/multiple-wallets/' | relative_url }})</h2>
+
+How to design for use cases where it is important to manage multiple wallets in a single application.
 
 </div>
 </div>