fix(v2): sitemap should respect the global trailingSlash config option.

[taylorreece]

Motivation

Sitemap has a depricated option, trailingSlash. When used, URLs in the sitemap have trailing slashes, but you see a warning:

Option "trailingSlash" of the sitemap plugin is deprecated: Please use the new Docusaurus global trailingSlash config instead, and the sitemaps plugin will use it.

If you remove the trailingSlash option from the sitemap plugin, and instead have a global trailingSlash option set to true, the generated sitemap lacks trailing slashes.

This PR causes the sitemap plugin to respect the global trailingSlash option.

Have you read the Contributing Guidelines on pull requests?

yes

Test Plan

Within website I explicitly set the global trailingSlash option to true, and then false, to verify that trailing slashes are generated (or not) respectively.

[netlify]

✔️ [V2]

🔨 Explore the source changes: a491d7c

🔍 Inspect the deploy log: https://app.netlify.com/sites/docusaurus-2/deploys/60dadd076764830008805905

😎 Browse the preview: https://deploy-preview-5068--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	84
🟢 Accessibility	98
🟢 Best practices	100
🟢 SEO	100
🟢 PWA	95

Lighthouse ran on https://deploy-preview-5068--docusaurus-2.netlify.app/

[slorber]

🤦 my PR didn't work #4950 I don't even read siteConfig 😅

thanks for noticing this!

It's not exactly how I want to fix this. The previous option should do "nothing" on trailingSlash: false (default option value) while applyTrailingSlash will actually remove a trailing slash (you may use slug: /x/y/z/ and don't want the trailing slash to be removed by default.

I'll edit your PR and add tests on monday

[taylorreece]

Awesome, thanks, @slorber !