Clarify usage of raster data cubes

documentation/1.0/datacubes.md

@@ -23,7 +23,9 @@ A vector cube on the other hand could look like this:
     <figcaption>An examplary vector datacube with 3 dimensions: 2 geometries are given for the vector dimension, along with 3 timesteps for the time dimension and 4 bands.</figcaption>
 </figure>
 
-Vector data cubes and raster data cubes are special cases of data cubes. A raster data cube has at least two spatial dimensions (x and y) and a vector data cube has at least a vector dimension.
+Vector data cubes and raster data cubes are special cases of data cubes. A raster data cube has at least two spatial dimensions (x and y) and a vector data cube has at least a dimension of type vector. Unfortunately, due to historical reasons, in openEO we currently **can not distinguish between a data cube and a raster data cube**. Therefore, we only distinguish between:
+* *vector data cubes* (i.e., a data cube **with** a dimension of type vector), and
+* non-vector data cubes (i.e., a data cube **without** a dimension of type vector), which we will simply refer to as a *raster data cubes* in the documentation.
 
 ## Dimensions