docs(changelog): move the voice geometry entries to a changelog.d fragment

The maintainer workflow asks runtime changes for a changelog.d/<pr>-<slug>.md
fragment and no edit to CHANGELOG.md. The three entries move unchanged, with
their credit, into changelog.d/846-voice-geometry.md.

changelog.d/846-voice-geometry.md

@@ -0,0 +1,15 @@
+- Voice can reuse what it outlines. `resolve_area` turns a named place into a
+  reusable area, keeping every part and hole, from the same sources as voice
+  outlines; a name several countries or states share ("Georgia", "Punjab") is
+  asked about unless the view is inside one of them. "Draw an area around
+  <landmark>" outlines the mapped area enclosing it, or a 250 m buffer marked
+  approximate. `analyst_query` counts inside an area, the area you drew or an
+  outline on the map, and `find_imagery` shows the best recent acquisition for
+  an area, the view or the spot under the pointer (manjunath22466, #846).
+- `osm_query` ("hospitals in Kathmandu") lists places of one kind into a
+  session-only OSM Places layer. It is offered only when `OVERPASS_UPSTREAMS`
+  is set, and `/api/osm/features` refuses before fetching otherwise; public
+  Nominatim is never used for it (manjunath22466, #846).
+- Analyst counts that combine flights, military aircraft and local ADS-B are
+  named "aircraft". Follow-ups keep the displayed scope and the loaded-data
+  caveat until a new scope replaces them (manjunath22466, #846).