chore: add code comments for autolinking (#1595)

## Description

Add code comments for few changes introduced in #1585. 

## Changes

Just few code comments. See the changes.


## Test code and steps to reproduce

--

## Checklist

- [x] Ensured that CI passes

android/src/main/jni/rnscreens.cpp

@@ -1,3 +1,7 @@
+/**
+ * This code was generated by [react-native-codegen](https://www.npmjs.com/package/react-native-codegen).
+ * @generated by codegen project: GenerateModuleJniCpp.js
+ */
 #include "rnscreens.h"
 
 namespace facebook {

android/src/main/jni/rnscreens.h

@@ -3,6 +3,19 @@
 #include <ReactCommon/JavaTurboModule.h>
 #include <ReactCommon/TurboModule.h>
 #include <jsi/jsi.h>
+
+/**
+ * Note this import and that it is not present in autogenerated header file
+ * under android/build/generated/source/codegen/jni/rnscreens.h
+ * 
+ * It is added here to make our custom symbols visible in autogenerated file with 
+ * code responsible for registering component descriptor providers. See that rncli.cpp, 
+ * located under <App>/android/app/build/generated/rncli/src/main/jni/rncli.cpp,
+ * includes autogenerated rnscreens.h header by default. We change this behaviour
+ * by appropriate include path configuration so that this header file gets included.
+ * 
+ * See: https://github.com/software-mansion/react-native-screens/pull/1585
+ */
 #include <react/renderer/components/rnscreens/RNSScreenComponentDescriptor.h>
 
 namespace facebook {