Python docstrings can have any format you like.

However, the standard tools for Python documentations support reStructuredText, which support multiple syntaxes for tables, e.g.:

=====  =====  =======
A      B      A and B
=====  =====  =======
False  False  False
True   False  False
False  True   False
True   True   True
=====  =====  =======

However, if this is as unfriendly as you think, you may want to consider splitting this single parameter into multiple simpler parameters.

Line blocks have a left margin value in the sphinx_rtd_theme. One way to get rid of them is to create a custom CSS file which imports the theme's style rules and add a rule for line blocks within tables without that margin. Assuming the standard file and path names of a Sphinx project:

Create a _static/css/mystyle.css file in your Sphinx project with the following content:

@import "theme.css";

table.docutils div.line-block {
    margin-left: 0;
}

Add the following option to the conf.py:

html_style = 'css/mystyle.css'

Rebuild the Sphinx project.