Automate sitemap generation #19

As our feed detail pages are typically hidden behind a search, we still want them to be discoverable by bots to be indexed on search engines. For this to be consistent, we will use a sitemap.

The sitemap is currently being generated by a script but done manually.

Objective

• Generate a sitemap automatically
• The sitemap to contain exclusively gtfs, gtfs_rt, and gbfs pages (search page + landing as well)
• There is a property in sitemaps 'lastmod' (last modified) -> this should reflect the actual date that the feed has changed and not just the date the sitemap was created.
• A method of when and how the sitemap will be generated (github actions?)
• Pick out a few key feeds (ex: MTA, Paris) and give them higher priority on the sitemap

Note

• Will need to call the db to get all the active feed ids to generate sitemap
• check google / best practices for sitemap update frequency