Pre-inclusion of cities with rapid transit networks

[bgo-eiu]

There are a finite number of cities large/dense enough for rapid transit, and a smaller number of those that have implemented it. It would be good if those could be included without a specific request for it, so that there is less of a barrier to entry or bias when people are mapping transit in new areas. For example, most cities in Nigeria do not have intra-city rapid transit, but Abuja does (https://en.wikipedia.org/wiki/Abuja_Light_Rail).

Likewise, it may even make sense to include the largest city and capital (if the two are different) for every country by default, since there would still be clear interest in mapping the bus network of a large city without rapid transit infrastructure.