Update existing CB docs

[SimonDarksideJ]

Summary

• Updated the existing CB doc with clarity and information on iOS/Android content building
• Added new guide for automation using the new "build-Content" action

[Copilot]

Pull request overview

This PR enhances the MonoGame Content Builder documentation by adding clarity to existing content and introducing comprehensive automation guidance. The updates include corrections to typos and grammar issues, new platform-specific instructions for iOS/Android content building, and a complete new guide for automating content builds using GitHub Actions.

• Fixed spelling and grammar issues in the existing Content Builder documentation
• Added detailed Android and iOS platform-specific bundling instructions with code examples
• Created comprehensive automation guide covering CI/CD workflows, multi-platform builds, and GitHub Actions integration

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 10 comments.

File	Description
articles/toc.yml	Added new table of contents entry for the automation guide
articles/getting_started/content_pipeline/content_builder_project.md	Fixed typos, added Android/iOS bundling sections, reorganized debugging scenarios, improved clarity throughout
articles/getting_started/content_pipeline/automating_content_builder.md	New comprehensive guide for automating MonoGame content building with GitHub Actions, including examples and troubleshooting

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