update doc

Author: b8raoult

docs/overview.rst

@@ -11,16 +11,24 @@ The array has the following dimensions:
 
 .. figure:: overview.png
    :alt: Data layout
+   :align: center
 
 The first dimension is the time dimension, the second dimension are the
 variables (e.g. temperature, pressure, etc), the third dimension is the
 ensemble, and fourth dimension are the grid points values.
 
+.. figure:: matrix.svg
+   :alt: Data chunking
+   :align: center
+
 This structure provides an efficient way to build the training dataset,
 as input and output of the model are simply consecutive slices of the
 array.
 
 .. literalinclude:: overview_.py
    :language: python
 
+
+
+
 .. _zarr: https://zarr.readthedocs.io/