feat: add Kotlin 2.1.20-Beta1 release details (#4621)

Author: koshachy

docs/images/eap/idea-kotlin-plugin-updates.png

@@ -24,7 +24,7 @@
 	</toc-element>
 	<toc-element toc-title="What's new in Kotlin">
 		<toc-element toc-title="Kotlin 2.1.0" accepts-web-file-names="whatsnew.html" topic="whatsnew21.md"/>
-		<toc-element toc-title="Kotlin 2.1.0-RC2" topic="whatsnew-eap.md" hidden="true"/>
+		<toc-element toc-title="Kotlin 2.1.20-Beta1" topic="whatsnew-eap.md"/>
 		<toc-element toc-title="Earlier versions">
 			<toc-element toc-title="Kotlin 2.0.20" topic="whatsnew2020.md"/>
 			<toc-element toc-title="Kotlin 2.0.0" topic="whatsnew20.md"/>
@@ -397,8 +397,7 @@
 	</toc-element>
 	<toc-element toc-title="Early access preview (EAP)">
 		<toc-element toc-title="Participate" topic="eap.md"/>
-		<toc-element toc-title="Install the Kotlin EAP Plugin" topic="install-eap-plugin.md"/>
-		<toc-element topic="configure-build-for-eap.md"/>
+		<toc-element topic="configure-build-for-eap.md" accepts-web-file-names="install-eap-plugin.html"/>
 	</toc-element>
 	<toc-element toc-title="Other resources">
 		<toc-element topic="faq.md"/>

docs/images/eap/idea-kotlin-update-channel.png

@@ -1,8 +1,10 @@
 [//]: # (title: Configure your build for EAP)
 
-If you create new projects using the EAP version of Kotlin, you don't need to perform any additional steps. The [Kotlin Plugin](install-eap-plugin.md) will do everything for you!
-
-You only need to configure your build manually for existing projects — projects that were created before installing the EAP version.
+<tldr>
+    <!-- <p>No preview versions are currently available</p> -->
+    <p>Latest Kotlin EAP release: <strong>%kotlinEapVersion%</strong></p>
+    <p><a href="eap.md#build-details">Explore Kotlin EAP release details</a></p>
+</tldr>
 
 To configure your build to use the EAP version of Kotlin, you need to: 
 
@@ -145,3 +147,9 @@ In the sample Maven project definition, replace `KOTLIN-EAP-VERSION` with the ac
     </build>
 </project>
 ```
+
+## If you run into any problems
+
+* Report an issue to [our issue tracker, YouTrack](https://kotl.in/issue).
+* Find help in the [#eap channel in Kotlin Slack](https://app.slack.com/client/T09229ZC6/C0KLZSCHF) ([get an invite](https://surveys.jetbrains.com/s3/kotlin-slack-sign-up)).
+* Roll back to the latest stable version: [change it in your build script file](configure-build-for-eap.md#adjust-the-kotlin-version).

docs/images/eap/idea-latest-kotlin-eap.png

@@ -1,10 +1,8 @@
 [//]: # (title: Participate in the Kotlin Early Access Preview)
 
-<!--
 <tldr>
     <p>Latest Kotlin EAP release: <strong>%kotlinEapVersion%</strong></p>
 </tldr>
--->
 
 You can participate in the Kotlin Early Access Preview (EAP) to try out the latest Kotlin features before they are released.
 
@@ -19,17 +17,14 @@ for everyone in [the growing Kotlin community](https://kotlinlang.org/community/
 If you have any questions and want to participate in discussions, you are welcome to join the [#eap channel in Kotlin Slack](https://app.slack.com/client/T09229ZC6/C0KLZSCHF). 
 In this channel, you can also get notifications about new EAP builds.
 
-**[Install the Kotlin EAP Plugin for IDEA or Android Studio](install-eap-plugin.md)**
+**[Configure your project for the Kotlin EAP version](configure-build-for-eap.md)**
 
 > By participating in the EAP, you expressly acknowledge that the EAP version may not be reliable, may not work as intended, and may contain errors.
 >
 > Please note that we don't provide any guarantees of compatibility between EAP and final versions of the same release. 
 >
 {style="note"}
 
-If you have already installed the EAP version and want to work on projects that were created previously, 
-check [our instructions on how to configure your build to support this version](configure-build-for-eap.md). 
-
 ## How the EAP can help you be more productive with Kotlin
 
 * **Prepare for the Stable release**. If you work on a complex multimodule project, participating in the EAP may streamline your experience when you adopt the Stable release version. The sooner you update to the Stable version, the sooner you can take advantage of its performance improvements and new language features. 
@@ -40,23 +35,21 @@ 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>2.1.0-RC2</strong>
-            <p>Released: <strong>November 18, 2024</strong></p>
-            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.1.0-RC2" target="_blank">Release on GitHub</a></p>
+        <td><strong>2.1.20-Beta1</strong>
+            <p>Released: <strong>December 19, 2024</strong></p>
+            <p><a href="https://github.com/JetBrains/kotlin/releases/tag/v2.1.20-Beta1" target="_blank">Release on GitHub</a></p>
         </td>
         <td>
-            <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-RC2">changelog</a> or <a href="whatsnew-eap.md">What's new in Kotlin 2.1.0-RC2</a>.</p>
+            <p>A tooling release with K2 kapt enabled by default.</p>
+            <p>For more details, please refer to the <a href="https://github.com/JetBrains/kotlin/releases/tag/v2.1.20-Beta1">changelog</a> or <a href="whatsnew-eap.md">What's new in Kotlin 2.1.20-Beta1</a>.</p>
         </td>
     </tr>
-</table>
--->
+</table>

docs/kr.tree

@@ -27,6 +27,9 @@ Pay special attention to the following restrictions concerning the use of the lo
 
 ## Kotlin mascot
 
+<primary-label ref="experimental-general"/>
+<secondary-label ref="eap"/>
+
 Kodee is Kotlin's reimagined mascot. More than just a symbol, Kodee is your friendly companion who’s there to encourage 
 and inspire you to express your creativity.
 When using it, we ask you to follow these [simple guidelines](https://resources.jetbrains.com/storage/products/kotlin/docs/Kotlin_Mascot_Guidelines.pdf).

docs/topics/configure-build-for-eap.md

@@ -77,5 +77,4 @@ Also, you could use package managers, such as [Homebrew](command-line.md#homebre
 
 * [Start your first project using IntelliJ IDEA IDE](jvm-get-started.md)
 * [Create a Multiplatform project with Fleet](https://www.jetbrains.com/help/kotlin-multiplatform-dev/fleet.html)
-* [Create your first cross-platform mobile app using Android Studio](https://www.jetbrains.com/help/kotlin-multiplatform-dev/multiplatform-create-first-app.html)
-* Learn how to [install EAP version of the Kotlin plugin](install-eap-plugin.md)
+* [Create your first cross-platform mobile app using Android Studio](https://www.jetbrains.com/help/kotlin-multiplatform-dev/multiplatform-create-first-app.html)