Update docs and README for GLCM texture (#963)

Add glcm_texture to the focal reference docs and to the README
feature matrix. CuPy/Dask+CuPy marked as CPU-fallback.

Author: brendancol

README.md

@@ -168,6 +168,7 @@ In the GIS world, rasters are used for representing continuous phenomena (e.g. e
 | [Emerging Hotspots](xrspatial/emerging_hotspots.py) | Classifies time-series hot/cold spot trends using Gi* and Mann-Kendall | ✅️ | ✅️ | ✅️ | ✅️ |
 | [Mean](xrspatial/focal.py) | Computes the mean value within a sliding neighborhood window | ✅️ | ✅️ | ✅️ | ✅️ |
 | [Focal Statistics](xrspatial/focal.py) | Computes summary statistics over a sliding neighborhood window | ✅️ | ✅️ | ✅️ | ✅️ |
+| [GLCM Texture](xrspatial/glcm.py) | Computes Haralick GLCM texture features over a sliding window | ✅️ | ✅️ | 🔄 | 🔄 |
 
 -------
 

docs/source/reference/focal.rst

@@ -26,6 +26,14 @@ Mean
    xrspatial.focal.mean
 
 
+GLCM Texture
+=============
+.. autosummary::
+   :toctree: _autosummary
+
+   xrspatial.glcm.glcm_texture
+
+
 Focal Statistics
 ================
 .. autosummary::