Update changelog formatting for version 6.0.0

Author: otarhe

README.md

@@ -54,7 +54,7 @@ The plugin can be downloaded from the GitHub repository and installed manually v
 
 ## **Changelog**
 
-= Version 6.0.0 (Mar 12, 2026) =
+#### **Version 6.0.0 (Mar 12, 2026)**
 * Added defensive mode feature for Edge Cache
 
 #### **Version 5.9.9 (Mar 08, 2026)**