Update Zudoku Sponsorship (#578)

Co-authored-by: Mike Bifulco <[email protected]>

Author: martyndavies

_includes/sponsor.html

@@ -5,7 +5,6 @@
     target="_blank"
     rel="noopener"
     class="pink"
-    >Zudoku</a
-  >
-  - Open-source, OpenAPI powered, highly customizable API documentation.
+    ><img src="/img/zudoku.png" alt="" width="110"></a>
+  - Open-source, highly customizable API documentation powered by OpenAPI.
 </div>