feature(sct_config): generate markdown as list

[fruch]

the table generated into docs/configuration_options.md was not very readable and more, and need to be vertical scrolling, that make it hard to work with.

this change is replacing the table with a header list of each configuration and make it a bit more readable and automaticlly linkable with no further tricks.

Testing

• [ ]

PR pre-checks (self review)

• I added the relevant backport labels
• I didn't leave commented-out/debugging code

Reminders

• Add New configuration option and document them (in sdcm/sct_config.py)
• Add unit tests to cover my changes (under unit-test/ folder)
• Update the Readme/doc folder relevant to this change (if needed)

[fruch]

example of a link into the new configuration docs:
https://github.com/fruch/scylla-cluster-tests/blob/update_config_markdown_to_list/docs/configuration_options.md#scylla_version--sct_scylla_version