Add adjustable padding for nested nodes and add storybook story for custom nested nodes

[ASchwad]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[X] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[X] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

The node content might get "covered" by nested nodes and there is currently no way to provide a padding for nodes within a node.

Issue Number: #28

What is the new behavior?

The padding towards nested nodes can now be adjusted for individual nodes.

Does this PR introduce a breaking change?

[ ] Yes
[X] No

Other information

Naming might be ambigous - Open for suggestions! maybe "innerPadding" or "nestedPadding" is more intuitive, because the actual node content is not affected by the padding.

[amcdnl]

Awesome stuff - few minor reqs

[ASchwad]

@amcdnl Integrated your feedback into the PR

[amcdnl]

need to fix the type otherwise lgtm

[amcdnl]

release 2.4.5 w/ this change