Add transit data acknowledgement

[graue]

The terms of the 511 transit data dump require this acknowledgement.

For new regions outside the Bay Area, the acknowledgement will only be displayed if it is defined by region-specific code.

Disables rel="noopener" lint rule, which is no longer relevant in modern browsers, as the "2021 update" on the very page the lint rule links to explains: https://mathiasbynens.github.io/rel-noopener/

[graue]

Forgot the screenshot:

It only displays if routes that use transit are presented