[Translations] Japanese ja_JP - Chapter 2,3

[nwiizo]

[Translations] Japanese ja_JP - Chapter 2,3

Description: Continues work on

• [Translations] Japanese ja_JP /kind documentation

Dear @salaboy and the platforms-on-k8s team,

First and foremost, I want to express my sincere gratitude for merging the Chapter 1 translation PR. Your support and trust in my work are truly appreciated.

Building on that momentum, this PR adds the Japanese translation for Chapter 2,3 of the "Platforms on Top of Kubernetes" book.

Changes include:

• Added Chapter 2,3 content to README-ja.md
• Ensured consistency in formatting and structure with the original English version and other translations
• Updated the table of contents in README-ja.md to reflect the addition of Chapter 2,3

As with the previous translation, I've put great effort into maintaining the accuracy and nuance of the original content while making it accessible to Japanese readers. I believe this continued translation will further expand the reach of this valuable resource within the Japanese-speaking Kubernetes and cloud-native community.

I welcome any feedback or suggestions for improvement. Please don't hesitate to point out any areas that need refinement or clarification.

Thank you once again for this opportunity to contribute to the project. I'm excited to continue this translation journey and look forward to your review.

Kind regards,

[salaboy]

@nwiizo I am merging this. but try to create a PR per chapter, it will be easier to keep track of the work

[nwiizo]

@salaboy Thank you for merging the translation! I'll create PRs for each chapter going forward - really appreciate your guidance on this.