Add docs for multiple native lib architectures insight (#15569)

## DESCRIBE YOUR PR
Adds documentation for the new Android multiple native library
architecture splits insight.

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Resolves EME-644

Author: rbro112

docs/platforms/android/size-analysis/insights.mdx

@@ -18,6 +18,7 @@ Below are a list of available insights for Android builds, followed by more deta
 | [WebP Optimization](#webp-optimization)                   | Tests PNG/JPEG bitmaps to see if lossless WebP would shrink them.     |
 | [Large Audio](#large-audio)                               | Surfaces hefty audio tracks that could be recompressed or trimmed.    |
 | [Hermes Debug Info (RN Only)](#hermes-debug-info-rn-only) | Points to bundled Hermes bytecode still carrying debugger metadata.   |
+| [Multiple Native Library Architectures](#multiple-native-library-architectures) | Detects when multiple native library architectures are packaged in an APK.   |
 
 ### Duplicate Files
 
@@ -106,3 +107,26 @@ You can tweak the bitrate (`b:a`) to balance quality vs. size. Higher bitrates (
 **What it is**: Detects Hermes bytecode bundles that still contain debug info sections.
 
 **How to fix**: Build the React Native bundle in release mode (`react-native bundle --dev false` or the Gradle release task) so Hermes strips debug sections before packaging.
+
+### Multiple Native Library Architectures
+
+**What it is**: Detects when multiple native libraries are packaged in an APK supporting different architectures. End user devices will only use one architecture (usually arm64_v8a), so most can be removed.
+
+**How to fix**: Upload an AAB to the Play Store (Google will automatically pass the architecture the end user needs). We also recommend you upload an AAB for size analysis.
+
+If you ship an APK, the `split {}` block can be used to output split APKs manually. If configured to skip ABI splits, Android will package all native library architectures into the main split.
+
+Ensure your split Gradle dls config has the `isEnabled = true` field set for the `abi {}` block.
+
+```kotlin
+android {
+  splits {
+    ..
+
+    abi {
+      isEnabled.set(true)
+    }
+  }
+}
+```
+More information about the ABI configuration for manual APK splits can be found in the [Android developer documentation](https://developer.android.com/studio/build/configure-apk-splits#configure-abi-split).