Unpurplify external links

Greenish is, uh, less shocking. I kept being confused. Other people
kept being confused. What in the world was I thinking? Why did this
of all things take me so long? How does one wake up? Take it from a
cat, it's probably not worth it...

Bug: T271632
Change-Id: I9b0225962e9103b8f0b33b6083dd564c47dbfb39

resources/themes/wikimedia.less

@@ -29,7 +29,7 @@
 @link-red: @red;
 @link-red-visited: @red-dark;
 
-@link-ext: #76b;
+@link-ext: #37a;
 @link-ext-visited: darken( @link-ext, 10% );
 
 // Flair