Make sure no one is going to old URL

[abettermap]

Not really a bug, but I noticed in Sentry at least one user hitting https://map.languagemapping.org/ within the past week. They were on iOS and arrived via the FB mobile site, so maybe it's from an old shared post or something?

Not the end of the world, should still work fine, but when users visit that address:

1. we won't be able to see their Sentry errors marked as "production" environment
2. Google Analytics won't pick up any of their activity
3. not 100% sure, depends on how domain and redirects are set up, but it might not help SEO (if we get to that point) to have two primary web addresses

So if there are any obvious places where the old URL is used (like my biz Instagram profile, oops!), fix it. Eventually we should phase out the old URL anyway.