add docs for h3PointDistKm

docs/en/sql-reference/functions/geo/h3.md

@@ -1064,4 +1064,41 @@ Result:
 └───────────────────┘
 ```
 
+## h3PointDistKm {#h3pointdistkm}
+
+Returns the "great circle" or "haversine" distance between pairs of GeoCoord points (latitude/longitude) pairs in kilometers.
+
+**Syntax**
+
+``` sql
+h3PointDistKm(lat1, lon1, lat2, lon2)
+```
+
+**Arguments**
+
+-   `lat1`, `lon1` — Latitude and Longitude of point1 in degrees. Type: [Float64](../../../sql-reference/data-types/float.md).
+-   `lat2`, `lon2` — Latitude and Longitude of point2 in degrees. Type: [Float64](../../../sql-reference/data-types/float.md).
+
+**Returned values**
+
+-  Haversine or great circle distance in kilometers.
+
+Type: [Float64](../../../sql-reference/data-types/float.md).
+
+**Example**
+
+Query:
+
+``` sql
+select h3PointDistKm(-10.0 ,0.0, 10.0, 0.0) as h3PointDistKm;
+```
+
+Result:
+
+``` text
+┌─────h3PointDistKm─┐
+│ 2223.901039504589 │
+└───────────────────┘
+```
+
 [Original article](https://clickhouse.com/docs/en/sql-reference/functions/geo/h3) <!--hide-->