update: Kotlin 2.3.21-RC2 eap release details (#5490)

Author: sarahhaggarty

docs/topics/eap.md

@@ -65,13 +65,13 @@ _No preview versions are currently available._
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-        <td><strong>2.3.21-RC</strong>
-            <p>Released: <strong>April 7, 2026</strong></p>
-            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.3.21-RC" target="_blank">Release on GitHub</a></p>
+        <td><strong>2.3.21-RC2</strong>
+            <p>Released: <strong>April 16, 2026</strong></p>
+            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.3.21-RC2" target="_blank">Release on GitHub</a></p>
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         <td>
             <p>A bug fix release with performance improvements for Kotlin 2.3.20.</p>
-            <p>For more details, refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.3.21-RC">changelog</a>.</p>
+            <p>For more details, refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.3.21-RC2">changelog</a> or <a href="whatsnew2320.md">What's new in Kotlin 2.3.20</a>.</p>
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