Update doc

Author: leafOfTree

README.md

@@ -5,7 +5,7 @@
 A utility that brings browser-style tabbed window management to the desktop.
 
 <p>
-<img alt="screenshot" src="https://raw.githubusercontent.com/leafOfTree/leafOfTree.github.io/master/WindowTabs-example.png" width="560" />
+<img alt="screenshot" src="https://raw.githubusercontent.com/leafOfTree/leafOfTree.github.io/master/WindowTabs-example.png" width="560" style="border-radius: 8px" />
 </p>
 
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