Robert Lancaster made huge improvements to the handling of Astrometry.net configuration management and indexes. This should make these features a lot more accessible to a wider pool of users.
You can edit the astrometry.net configuration file directly in KStars. Furthermore, you can easily add/remove folders that that contain the index files. Many users have the indexes files stored in external hard drivers, and with this feature, it is now very easy to add the additional folders so they get utilized by the solver.
This change is accompanied by changes to the index downloader. Now you can check all your collections, and you have the ability to download indexes to a particular folder in your collection. A green index file indicates that the file is available in the system and does not require to be downloaded.