Fix warnings in docs generation

[noxan]

Setup: Follow contribution guidelines on how to setup the docs

Reproduce: Build the docs withcd docs && make html

Task: Fix the docstring warnings listed below, short google search on what the issue means exactly often helps.

Output:

/neural_prophet/docs/source/contents.rst:88: WARNING: toctree contains reference to nonexisting document 'benchmarking'
/neural_prophet/neuralprophet/forecaster.py:docstring of neuralprophet.forecaster.NeuralProphet:6: WARNING: Bullet list ends without a blank line; unexpected unindent.
/neural_prophet/neuralprophet/forecaster.py:docstring of neuralprophet.forecaster.NeuralProphet:94: ERROR: Unexpected indentation.
/neural_prophet/neuralprophet/forecaster.py:docstring of neuralprophet.forecaster.NeuralProphet:89: WARNING: Block quote ends without a blank line; unexpected unindent.
/neural_prophet/neuralprophet/forecaster.py:docstring of neuralprophet.forecaster.NeuralProphet.plot_parameters:26: CRITICAL: Unexpected section title.

Note
----
/neural_prophet/neuralprophet/forecaster.py:docstring of neuralprophet.forecaster.NeuralProphet.split_df:47: ERROR: Unexpected indentation.
/neural_prophet/docs/source/future-regressors.md:3: ERROR: Document or section may not begin with a transition.
/neural_prophet/neuralprophet/time_dataset.py:docstring of neuralprophet.time_dataset.fourier_series:3: WARNING: Bullet list ends without a blank line; unexpected unindent.
/neural_prophet/neuralprophet/time_net.py:docstring of neuralprophet.time_net.DeepNet.forward:1: WARNING: Definition list ends without a blank line; unexpected unindent.
/neural_prophet/neuralprophet/time_net.py:docstring of neuralprophet.time_net.FlatNet:1: WARNING: Inline literal start-string without end-string.
/neural_prophet/neuralprophet/time_net.py:docstring of neuralprophet.time_net.FlatNet:1: WARNING: Inline literal start-string without end-string.
looking for now-outdated files... none found
pickling environment... done
checking consistency... /neural_prophet/docs/source/Live_plot_during_training.nblink: WARNING: document isn't included in any toctree
/neural_prophet/docs/source/Prophet_to_TorchProphet.nblink: WARNING: document isn't included in any toctree
/neural_prophet/docs/source/global_local_modeling.nblink: WARNING: document isn't included in any toctree
/neural_prophet/docs/source/global_modeling.nblink: WARNING: document isn't included in any toctree
/neural_prophet/docs/source/network_architecture_visualization.nblink: WARNING: document isn't included in any toctree
/neural_prophet/docs/source/plotly.nblink: WARNING: document isn't included in any toctree
/neural_prophet/docs/source/uncertainty_estimation.nblink: WARNING: document isn't included in any toctree
done
preparing documents... done
writing output... [100%] utils
/neural_prophet/docs/source/auto-regression.md:48: WARNING: 'myst' reference target not found: ../hyperparameter-selection.md#regularization-related-parameters
/neural_prophet/docs/source/seasonality.md:55: WARNING: 'myst' reference target not found: ../hyperparameter-selection.md#regularization-related-parameters

[noxan]

• https://github.com/rmcgibbo/doccheck
• https://numpydoc.readthedocs.io/en/latest/validation.html
• https://github.com/pycqa/doc8
• https://pypi.org/project/rstcheck/
• https://github.com/scikit-learn/scikit-learn/blob/main/sklearn/tests/test_docstrings.py
• https://github.com/PyCQA/pydocstyle and https://pypi.org/project/flake8-docstrings/

[noxan]

Seems this might be one of the problems: https://stackoverflow.com/questions/71374618/sphinx-autodoc-with-napoleon-google-doc-string-style-warnings-and-errors-abou

[noxan]

• https://www.sphinx-doc.org/en/master/usage/extensions/napoleon.html#module-sphinx.ext.napoleon
• https://www.sphinx-doc.org/en/master/usage/extensions/example_numpy.html#example-numpy
• https://stackoverflow.com/questions/71374618/sphinx-autodoc-with-napoleon-google-doc-string-style-warnings-and-errors-abou

[noxan]

• https://github.com/numpy/numpydoc/
• https://github.com/adamchainz/blacken-docs

[noxan]

I find it impossible to understand where most of those docstring issues lie...