Fixes #1 - Implement external link icon

pages/images.md

Index: pages/images.md
===================================================================
--- a/pages/images.md
+++ b/pages/images.md
@@ -1,16 +1,17 @@
 title=Images
 description=Shared image files for eyeo websites.
 
 # Images
 
 Shared image files for eyeo websites.
 
 1. [App store badges](#app-store-badges)
+1. [External link icon](#external-link)
 
 ## App store badges { #app-store-badges }
 
 ### Apple App Store
 
 <img src="img/png/apple-app-store-badge.png" srcset="img/svg/apple-app-store-badge.svg 2x" alt="Download on the App Store" width="200">
 
 ```
@@ -27,8 +28,39 @@
 
 ```
 ![Get it on Google Play](img/png/google-play-badge.png)
 ```
 
 ```
 <img src="img/png/google-play-badge.png" alt="Get it on Google Play">
 ```
+
+## External link icon { #external-link }
+
+![External link icon](/img/png/external-icon-black.png)
+
+The external link icon is used to identify links that 1) outside the current domain and 2) open in a new window.
+
+Available in two colours:
+
+- `external-icon-black`
+- `external-icon-white`
+
+```
+[Example.com ![External link icon]()](https://example.com)
+```
+
+```
+<a href="https://example.com" target="_blank">
+  Example.com
+  <img src="/img/png/external-icon-black.png"
+       srcset="/img/svg/external-icon-black.svg 2x"
+       alt="External link icon">
+</a>
+```
+
+<a href="https://example.com" target="_blank">
+  Example.com
+  <img src="/img/png/external-icon-black.png"
+       srcset="/img/svg/external-icon-black.svg 2x" 
+       alt="External link icon" style="height: 1em;">
+</a>