Add documentation about single-line-diagram layout parameters

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• Do you want to request a feature or report a bug? Feature

• What is the current behavior? There is no documentation to explain all the layout parameters available in single-line-diagram. We need a short functional description for each of them, ideally with a svg illustrating the changes.

• What is the motivation / use case for changing the behavior? Help the users of single-line-diagram customizing the algorithm, and promote the new features! but that might also lead to a clean up (some old parameters seemed to be useless now)

• Other information Note that a link to that required page was already created in PR #161

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What would be nice is for each parameter:

• a short description
• two screenshots to understand what it changes clearly (default value / modified value for instance)

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The page should be located next to the "svg-writing" API guide. It should be referenced in the API guide index, in the powsybl-single-line-diagram repository page and in the tutorials index.