[DOC] Downloadable PDF Developer Guides

[aryasoni98]

Description

This PR implements downloadable PDF generation for OpenSearch developer guides and documentation collections. The feature enables users to download complete documentation guides as PDF files, providing:

1. Enhanced Searchability: Users can perform comprehensive Ctrl+F searches across entire documentation guides in a single PDF document
2. AI Tool Integration: PDFs can be uploaded to AI tools like ChatGPT custom GPTs, NotebookLM, and similar platforms for knowledge summarization and question-answering
3. Offline Access: Users can access documentation without an internet connection

Implementation Details:

• Created a Jekyll generator plugin (_pdf_generator/pdf_generator.rb) that generates PDFs during the build process
• All PDF-related code is contained in a single _pdf_generator/ folder as requested
• Uses the grover Ruby gem (Puppeteer-based) for high-quality PDF generation from HTML
• PDFs are automatically generated during Jekyll build and saved to _site/pdfs/ directory
• PDFs will be accessible at https://docs.opensearch.org/pdfs/{filename}.pdf when deployed
• Configurable via _config.yml to specify which collections/guides should generate PDFs
• Includes professional PDF formatting with cover pages, table of contents, and styled content

Files Added:

• _pdf_generator/pdf_generator.rb - Main plugin implementation
• _pdf_generator/README.md - Documentation for the PDF generator
• _plugins/pdf_generator_loader.rb - Minimal loader to ensure Jekyll loads the plugin

Files Modified:

• Gemfile - Added grover gem dependency
• _config.yml - Added PDF generator configuration section and plugin registration

Issues Resolved

Closes #11192

Version

all

Frontend features

N/A - This is a backend build-time feature that generates downloadable PDF files.

Checklist

• By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and subject to the Developers Certificate of Origin.

[github-actions]

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[kolchfa-aws]

@peterzhuamazon Could you review this PR?