docs: refine README usage and ecosystem note

Author: afc163

README.md

@@ -1,14 +1,10 @@
 <div align="center">
   <h1>@rc-component/dropdown</h1>
+  <p><sub>Part of the Ant Design ecosystem.</sub></p>
   <p>🔽 A trigger-driven dropdown component for React.</p>
-
-  <a href="https://ant.design">
-    <img width="32" height="32" src="https://gw.alipayobjects.com/zos/rmsportal/KDpgvguMpGfqaHPjicRK.svg" alt="Ant Design" />
-  </a>
-
-  <p>Part of the Ant Design ecosystem.</p>
 </div>
 
+
 <div align="center">
 
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