docs: document Cordova package.json fields

[MasterIfeanyi]

Platforms affected

All platforms. Documentation only.

Motivation and Context

Closes #1005.

Cordova projects use package.json alongside config.xml, but there is currently no reference documentation for the Cordova-specific fields maintained by the CLI. This makes it difficult to understand which fields are managed automatically and when they are updated.

Description

Added a new package.json API reference page documenting:

• name, displayName, and version
• cordova.platforms
• cordova.plugins
• devDependencies
• When and how the Cordova CLI updates these fields
• The effect of the --nosave option

Also added the new reference page to the documentation table of contents.

Testing

• Ran the documentation build with npm run build.
• Ran git diff --check to verify there are no whitespace errors.
• Verified that the generated TOC is produced successfully.

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

AI usage disclosure: AI assistance was used to help review and refine the documentation wording and PR description. The changes were reviewed and verified by the contributor.