docs(changelog): add the #1558 fragment

changelog.d/1558-satellite-classes.md

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+- File satellites under six classes, Stations, Imaging, Telecom, Starlink,
+  Probes and Debris, each with a toggle; Stations and Imaging show by default.
+  Classes come from CelesTrak SATCAT, the UCS Satellite Database and name rules
+  (Denis Groshev, @ZloyS, #1558).