Improve Documentation for Custom Starters in kedro new (#2618)

[doxenix]

Subject:

This pull request aims to enhance the user experience and clarity of documentation within kedro new command for custom starters. Specifically, it addresses issue #2618

[astrojuanlu]

@doxenix There seem to be commits from other branches here, do you mind squashing everything and rebasing on top of main? There are also conflicts in the changelog.

Also remember to signoff your commit so the DCO check passes. If you click on it you will find instructions. If it was only one commit you can do git commit --amend --signoff --no-edit, if you had more, git rebase --signoff. After rewriting the history you will need to do git push --force.

And if you keep working on this branch, please use the -s/--signoff flag when committing, for example git commit -s -m 'Add feature'.