feat: Kotlin 2.1.0-Beta1 EAP release details (#4434)

* feat: Kotlin 2.1.0-Beta1 EAP release details

* fix: fix the version

* fix: review

* chore: uncomment a link to language proposals

* chore: Ale's review

Author: koshachy

docs/kr.tree

@@ -35,7 +35,7 @@
     <toc-element toc-title="What's new in Kotlin">
         <toc-element id="whatsnew2020.md" toc-title="Kotlin 2.0.20" accepts-web-file-names="whatsnew.html"/>
         <toc-element id="whatsnew20.md" toc-title="Kotlin 2.0.0"/>
-        <toc-element id="whatsnew-eap.md" toc-title="Kotlin 2.0.20-RC2" hidden="true"/>
+        <toc-element id="whatsnew-eap.md" toc-title="Kotlin 2.1.0-Beta1"/>
         <toc-element toc-title="Earlier versions">
             <toc-element id="whatsnew1920.md" toc-title="Kotlin 1.9.20"/>
             <toc-element id="whatsnew19.md" toc-title="Kotlin 1.9.0"/>

docs/topics/eap.md

@@ -40,23 +40,21 @@ check [our instructions on how to configure your build to support this version](
 
 ## Build details
 
- _No preview versions are currently available._ 
+<!--  _No preview versions are currently available._ --> 
 
-<!--
 <table>
     <tr>
         <th>Build info</th>
         <th>Build highlights</th>
     </tr>
     <tr>
-        <td><strong>2.0.20-RC2</strong>
-            <p>Released: <strong>August 13, 2024</strong></p>
-            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.0.20-RC2" target="_blank">Release on GitHub</a></p>
+        <td><strong>2.1.0-Beta1</strong>
+            <p>Released: <strong>September 17, 2024</strong></p>
+            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.1.0-Beta1" target="_blank">Release on GitHub</a></p>
         </td>
         <td>
-            <p>A tooling release for Kotlin 2.0.0</p>
-            <p>For more details, please refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.0.20-RC2">changelog</a> or <a href="whatsnew-eap.md">What's new in Kotlin 2.0.20-RC2</a>.</p>
+            <p>A language release with previews of new features and tooling updates.</p>
+            <p>For more details, please refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.1.0-Beta1">changelog</a> or <a href="whatsnew-eap.md">What's new in Kotlin 2.1.0-Beta1</a>.</p>
         </td>
     </tr>
 </table>
--->