Update 2.3_data_access.md

Some fixes

lectures/2.3_data_access/2.3_data_access.md

@@ -43,7 +43,7 @@ With the Pangeo ecosystem, the STAC Catalogue Python Library `pystac_client` is
 
 - [pystac_client](https://pystac-client.readthedocs.io/en/stable/)
 - [stackstac](https://stackstac.readthedocs.io/en/latest/)
-- [xarray](http://xarray-datatree.readthedocs.io)
+- [xarray](https://docs.xarray.dev/en/stable/index.html)
 
 ## Processes on Datacubes
 
@@ -71,13 +71,15 @@ In the image, the example datacube can be seen at the top with labeled dimension
 
 Exercise 2.3 on Data Access Filter can be completed using both openEO and the Pangeo ecosystem:
 - [Exercise 2.3 Data Access Filter with openEO](https://github.com/EO-College/cubes-and-clouds/blob/main/lectures/2.3_data_access/exercises/openeo/23_openeo_data_access_filter.ipynb)
-- [Exercise 2.3 Data Access Filter with Pangeo](https://github.com/EO-College/cubes-and-clouds/blob/main/lectures/2.3_data_access/exercises/pangeo/23_pangeo_data_access_filter.ipynb). You might find the following documentation helpful for understanding Jupyter Notebooks: [Pangeo - Indexing and selecting data with xarray](https://docs.xarray.dev/en/latest/user-guide/indexing.html).
+- [Exercise 2.3 Data Access Filter with Pangeo](https://github.com/EO-College/cubes-and-clouds/blob/main/lectures/2.3_data_access/exercises/pangeo/23_pangeo_data_access_filter.ipynb).
+
+This additional documentation is helpful to understand the previous exercises: [Xarray - Indexing and selecting data](https://docs.xarray.dev/en/latest/user-guide/indexing.html).
 
 ### Apply
 
 The `apply*` functions employ a process on the datacube that calculates new pixel values for each pixel, based on `n` other pixels. 
 
-With openEO, the following `apply*` functions can be used: [`apply`](https://processes.openeo.org/#apply), [`apply_neighborhood`](https://processes.openeo.org/#apply_neighborhood), [`apply_dimension`](https://processes.openeo.org/#apply_dimension)).
+With openEO, the following `apply*` functions can be used: [`apply`](https://processes.openeo.org/#apply), [`apply_neighborhood`](https://processes.openeo.org/#apply_neighborhood), [`apply_dimension`](https://processes.openeo.org/#apply_dimension), [`apply_kernel`](https://processes.openeo.org/#apply_kernel).
 
 Similarly, with Pangeo, the `apply` and `apply_ufunc` functions in `xarray` allow operations on multidimensional arrays, where new values are calculated for each element based on surrounding data, similar to the apply functions in openEO.