[atlas] New: Atlas resource coverage (and more maps!) beta

Dear Atlas Users,

Today we enabled another interesting feature (in beta mode, for now):
details about what networks Atlas covers at the moment. This feature lists
IPv4/IPv6 prefixes, ASNs and countries. This information will also be used
for User Defined Measurements, in order to filter vantage points to specific
networks or locations.

You can access this at https://atlas.ripe.net/atlas/coverage.html

Background information:
* the prefixes and ASNs are looked up in RIS, based on the address of the probe
* the country code is looked up in OpenStreetMaps based on the probe geolocation

We are aware that in some cases the lookup has a surprising result. One
example is 6to4: for IPv6 related ASNs the prefix is 2002::/16 but the ASN
can be misleading. We'll most likely stop looking up ASNs for 6to4 (and
Teredo) prefixes. If you see anomalies *not* related to this, you can let us
know at atlas-dev at ripe.net

Regards,
Robert, for the whole team