Update cover image

Author: iamprogrammerlk

readme.md

@@ -4,8 +4,8 @@
 <br>
 
 <div align="center" style="text-align: center;">
-  <a target="_blank" rel="noreferrer" href="https://prettybash.github.io">
-    <img src="resource/cover_3840x2160.png" alt="PrettyBash" width="100%">
+  <a target="_blank" href="https://prettybash.github.io">
+    <img src="resource/prettybash_logo_cover_3840×2160.png" alt="PrettyBash" width="100%">
   </a>
 </div>