Add comment for canOverrideExistingModule in ReactModuleInfo cons…

…tructor on Android (#6877)

## Summary

This PR adds a comment in `ReactModuleInfo` constructor in
ReanimatedPackage.java.

We set `canOverrideExistingModule` to `true` because Reanimated
overrides `UIManagerModule`.

## Test plan

packages/react-native-reanimated/android/src/main/java/com/swmansion/reanimated/ReanimatedPackage.java

@@ -58,7 +58,7 @@ public ReactModuleInfoProvider getReactModuleInfoProvider() {
           new ReactModuleInfo(
               reactModule.name(),
               moduleClass.getName(),
-              true,
+              true, // override UIManagerModule
               reactModule.needsEagerInit(),
               reactModule.isCxxModule(),
               BuildConfig.IS_NEW_ARCHITECTURE_ENABLED));