mention pyspark licence and add comment about delta.io

Signed-off-by: Tobias Windisch <tobias.windisch@hs-kempten.de>

README.md

@@ -96,6 +96,7 @@ Please have a look at our [contribution guide](https://boschglobal.github.io/lui
 | [pipdeptree](https://github.com/tox-dev/pipdeptree)|[MIT License](https://github.com/tox-dev/pipdeptree/blob/main/LICENSE) | Dependency |
 | [requirements-parser](https://github.com/madpah/requirements-parser)|[Apache License 2.0](https://github.com/madpah/requirements-parser/blob/master/LICENSE)| Dependency |
 | [pyarrow](https://github.com/apache/arrow)|[Apache License 2.0](https://github.com/apache/arrow/blob/master/LICENSE.txt)| Dependency |
+| [spark](https://github.com/apache/spark)|[Apache License 2.0](https://github.com/apache/spark/blob/master/LICENSE)| Dependency |
 
 ## Development dependency
 

docs/source/conf.py

@@ -93,7 +93,7 @@
 intersphinx_mapping = {
     'sphinx': ('http://www.sphinx-doc.org/en/master', None),
     'python': ('https://docs.python.org/' + python_version, None),
-    'matplotlib': ('https://matplotlib.org', None),
+    'matplotlib': ('https://matplotlib.org/stable', None),
     'numpy': ('https://numpy.org/doc/stable/', None),
     'pandas': ('https://pandas.pydata.org/pandas-docs/stable', None),
 }

docs/source/decorators.rst

@@ -129,6 +129,12 @@ cloud storages, we provide input decorators that render the usage of
 See :ref:`pyspark` for more details on how to implement pipelines
 using these inputs.
 
+
+.. note::
+
+   Make sure that the `delta-spark` extension is installed into your
+   spark cluster. See more `here <https://docs.delta.io>`_.
+
 Directory structure
 -------------------
 The following decorators denote the directory in the project directory

docs/source/tutorials/spark.rst

@@ -72,6 +72,11 @@ however, persists its output into a pickle file, which requires
 :py:mod:`luisy` to serialize all the data to a
 :py:mod:`pandas.DataFrame` beforehand.
 
+.. note::
+
+   Make sure that the `delta-spark` extension is installed into your
+   spark cluster. See more `here <https://docs.delta.io>`_.
+
 Running a pipeline
 ------------------