Submit new sitemaps to search providers.

[johnnymatthews]

This is a follow up from #505. We need to give the new site maps over to Google, Bing, DuckDuckGo, and any other major search providers so they're up to date.

• Install Vuepress Sitemap plugin.
• Generate sitemap.
• Add sitemap location to robots.txt, something like Sitemap: http://example.com/sitemap_location.xml. More info from Google here.
• Ping Google to re-crawl the site: http://www.google.com/ping?sitemap=https://example.com/sitemap.xml.

[cwaring]

there is currently no sitemap generated for the docs beta due to the beta crawler visibility. this plugin needs to be installed and configured.

[johnnymatthews]

Lovely. Added that step to the issue.

[cwaring]

grand, I'm trying to follow along to add context where I can

[hugomrdias]

this is done, everything will be updated when we release to production