docs: Add polars-h3 and polars-st to plugin list (#20653)

docs/source/user-guide/plugins/index.md

@@ -268,16 +268,29 @@ understanding.
 
 Here is a curated (non-exhaustive) list of community-implemented plugins.
 
+### Various
+
 - [polars-xdt](https://github.com/pola-rs/polars-xdt) Polars plugin with extra datetime-related
   functionality which isn't quite in-scope for the main library
+- [polars-hash](https://github.com/ion-elgreco/polars-hash) Stable non-cryptographic and
+  cryptographic hashing functions for Polars
+
+### Data science
+
 - [polars-distance](https://github.com/ion-elgreco/polars-distance) Polars plugin for pairwise
   distance functions
 - [polars-ds](https://github.com/abstractqqq/polars_ds_extension) Polars extension aiming to
   simplify common numerical/string data analysis procedures
-- [polars-hash](https://github.com/ion-elgreco/polars-hash) Stable non-cryptographic and
-  cryptographic hashing functions for Polars
+
+### Geo
+
+- [polars-dt](https://github.com/Oreilles/polars-st) Polars ST provides spatial operations on Polars
+  DataFrames, Series and Expressions. Just like Shapely and Geopandas.
 - [polars-reverse-geocode](https://github.com/MarcoGorelli/polars-reverse-geocode) Offline reverse
-  geocoder for finding the closest city to a given (latitude, longitude) pair
+  geocoder for finding the closest city to a given (latitude, longitude) pair.
+- [polars-h3](https://github.com/Filimoa/polars-h3) This is a Polars extension that adds support for
+  the H3 discrete global grid system, so you can index points and geometries to hexagons directly in
+  Polars.
 
 ## Other material