feat: troubleshooting section in migration guide (#3918)

* Update: troubleshooting section in migration guide

* SME reviews

* Daniel review

* chore: fix code snippet

docs/topics/dokka-migration.md

@@ -438,8 +438,75 @@ DGP v2 now supports Gradle build cache and configuration cache, improving build
 * To enable build cache, follow instructions in the [Gradle build cache documentation](https://docs.gradle.org/current/userguide/build_cache.html#sec:build_cache_enable).
 * To enable configuration cache, follow instructions in the [Gradle configuration cache documentation](https://docs.gradle.org/current/userguide/configuration_cache.html#config_cache:usage:enable ).
 
+## Troubleshooting
+
+In large projects, Dokka can consume a significant amount of memory to generate documentation.
+This can exceed Gradle’s memory limits, especially when processing large volumes of data.
+
+When Dokka generation runs out of memory, the build fails, and Gradle can throw exceptions like `java.lang.OutOfMemoryError: Metaspace`.
+
+Active efforts are underway to improve Dokka's performance, although some limitations stem from Gradle.
+
+If you encounter memory issues, try these workarounds:
+
+* [Increasing heap space](#increase-heap-space)
+* [Running Dokka within the Gradle process](#run-dokka-within-the-gradle-process)
+
+### Increase heap space
+
+One way to resolve memory issues is to increase the amount of Java heap memory for the Dokka generator process. 
+In the `build.gradle.kts` file, adjust the 
+following configuration option:
+
+```kotlin
+dokka {
+    // Dokka generates a new process managed by Gradle
+    dokkaGeneratorIsolation = ProcessIsolation {
+        // Configures heap size
+        maxHeapSize = "4g"
+    }
+}
+```
+
+In this example, the maximum heap size is set to 4 GB (`"4g"`). Adjust and test the value to find the optimal setting for your build.
+
+If you find that Dokka requires a considerably expanded heap size, for example, significantly higher than Gradle's own memory usage, 
+[create an issue on Dokka's GitHub repository](https://kotl.in/dokka-issues).
+
+> You have to apply this configuration to each subproject. It's recommended that you configure Dokka in a convention 
+> plugin applied to all subprojects.
+>
+{style="note"}
+
+### Run Dokka within the Gradle process
+
+When both the Gradle build and Dokka generation require a lot of memory, they may run as separate processes, 
+consuming significant memory on a single machine.
+
+To optimize memory usage, you can run Dokka within the same Gradle process instead of as a separate process. This 
+allows you to configure the memory for Gradle once instead of allocating it separately for each process.
+
+To run Dokka within the same Gradle process, adjust the following configuration option in the `build.gradle.kts` file:
+
+```kotlin
+dokka {
+    // Runs Dokka in the current Gradle process
+    dokkaGeneratorIsolation = ClassLoaderIsolation()
+}
+```
+
+As with [increasing heap space](#increase-heap-space), test this configuration to confirm it works well for your project.
+
+For more details on configuring Gradle's JVM memory, see the [Gradle documentation](https://docs.gradle.org/current/userguide/config_gradle.html#sec:configuring_jvm_memory).
+
+> Changing the Java options for Gradle launches a new Gradle daemon, which may stay alive for a long time. You can [manually stop any other Gradle processes](https://docs.gradle.org/current/userguide/gradle_daemon.html#sec:stopping_an_existing_daemon).
+> 
+> Additionally, Gradle issues with the `ClassLoaderIsolation()` configuration may [cause memory leaks](https://github.com/gradle/gradle/issues/18313). 
+>
+{style="note"}
+
 ## What's next
 
 * Explore more [DGP v2 project examples](https://github.com/Kotlin/dokka/tree/master/examples/gradle-v2). 
 * [Get started with Dokka](dokka-get-started.md).
-* [Learn more about Dokka plugins](dokka-plugins.md).
+* [Learn more about Dokka plugins](dokka-plugins.md).