BioPsyKit Doc Improvements

Bullet list in parameters

Change this:

Specify specialized color palette (or ``None`` to return default palette). Default: ``None``.
Available palette types:
    * ``line_2``: For line plots with two elements
    * ``line_3``: For line plots with three elements
    * ``ensemble_3``: For ensemble plots (mean ± std) with three elements
    * ``box_2``: For boxplots with two elements

To this:

Specify specialized color palette (or ``None`` to return default palette). Default: ``None``.
Available palette types:

* ``line_2``: For line plots with two elements
* ``line_3``: For line plots with three elements
* ``ensemble_3``: For ensemble plots (mean ± std) with three elements
* ``box_2``: For boxplots with two elements

None reference in docstring

None links are because there is a wrong reference. Example:

Change this:

See Also
--------
`load_dataset_nilspod`
    load single NilsPod dataset

To this:

See Also
--------
:func:`load_dataset_nilspod`
    load single NilsPod dataset

WARNING: Bullet list ends without a blank line; unexpected unindent.

Change this:

how to handle if counter of dataset is not monotonously increasing, which might be an indicator for a
corrupted dataset:
    * ``raise``: raise an error
    * ``warn``: issue a warning but still return a dataframe
    * ``ignore``: ignore the counter check result
Default: ``raise``

to this:

how to handle if counter of dataset is not monotonously increasing, which might be an indicator for a
corrupted dataset:
* ``raise`` (default): raise an error
* ``warn``: issue a warning but still return a dataframe
* ``ignore``: ignore the counter check result

Wrong indentation

Change this:

* "end_only": if less than 50% of all samples are corrupted and corrupted samples
are only in the last third of the dataset

to this:

* "end_only": if less than 50% of all samples are corrupted and corrupted samples
  are only in the last third of the dataset