Update readme

README.md

@@ -1,7 +1,8 @@
-<p align="center"><b>:warning: CAUTION! THIS IS A BETA VERSION OF LINKACE! :warning:</b></p>
-
 <p align="center">
-  <img src="https://www.linkace.org/images/linkace-social.jpg" title="Linkace">
+  <picture>
+    <source media="(prefers-color-scheme: dark)" srcset="https://www.linkace.org/images/linkace-social-dark-transparent.png">
+    <img src="https://www.linkace.org/images/linkace-social.jpg" alt="Linkace">
+  </picture>
 </p>
 
 <p align="center"><b>Your self-hosted tool for effortlessly archiving, organizing, and sharing your favorite web links.</b></p>