Update Lights On logo

Author: tomchristie

docs/img/premium/lightson-readme.png

@@ -74,7 +74,7 @@ continued development by **[signing up for a paid plan][funding]**.
     <li><a href="https://cadre.com" style="background-image: url(https://fund-rest-framework.s3.amazonaws.com/cadre.png)">Cadre</a></li>
     <li><a href="https://loadimpact.com/?utm_campaign=Sponsorship%20links&utm_source=drf&utm_medium=drf" style="background-image: url(https://fund-rest-framework.s3.amazonaws.com/load-impact.png)">Load Impact</a></li>
     <li><a href="https://hubs.ly/H0f30Lf0" style="background-image: url(https://fund-rest-framework.s3.amazonaws.com/kloudless.png)">Kloudless</a></li>
-    <li><a href="https://lightsonsoftware.com" style="background-image: url(https://fund-rest-framework.s3.amazonaws.com/lightson.png)">Lights On Software</a></li>
+    <li><a href="https://lightsonsoftware.com" style="background-image: url(https://fund-rest-framework.s3.amazonaws.com/lightson-dark.png)">Lights On Software</a></li>
 </ul>
 <div style="clear: both; padding-bottom: 20px;"></div>