docs: updated quadtree region in the API ref.

Author: pabloitu

docs/reference/api_reference.rst

@@ -207,7 +207,18 @@ Region class(es):
     :toctree: generated
 
     CartesianGrid2D
+    CartesianGrid2D.from_origins
+    CartesianGrid2D.from_dict
+    CartesianGrid2D.to_dict
     CartesianGrid2D.get_cartesian
+    CartesianGrid2D.get_cell_area
+    CartesianGrid2D.get_index_of
+
+    QuadtreeGrid2D
+    QuadtreeGrid2D.from_catalog
+    QuadtreeGrid2D.from_single_resolution
+    QuadtreeGrid2D.from_quadkeys
+    QuadtreeGrid2D.get_cartesian
 
 Testing regions: