Fix & Instruction of adding manual native package

[aajahid]

Proper Kotlin syntax and instruction on how to add native package manually.
I followed the official documentation and applied the "Kotlin" syntax. I believe it had the leftover comment/instruction of java syntax, which I replaced with Kotlin syntax.

Summary:

The comment/instruction on manual native package isn't correct. Also the existing code isn't intuitive for developer to easily add a native package manually.

Changelog:

[ANDROID] [CHANGED] - Allowed developer easily add a native package manually, with proper instruction.

Test Plan:

Applied the change from the official docs - https://reactnative.dev/docs/native-modules-android?android-language=kotlin
Also in my own project - I was able to add native package manually using that syntax.

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	16,525,132	-8
android	hermes	armeabi-v7a	n/a	--
android	hermes	x86	n/a	--
android	hermes	x86_64	n/a	--
android	jsc	arm64-v8a	19,899,938	+5
android	jsc	armeabi-v7a	n/a	--
android	jsc	x86	n/a	--
android	jsc	x86_64	n/a	--

Base commit: 43826fa
Branch: main

[aajahid]

Closing as already another PR with same fix got merged.

#41856