Create doubly_linked_list2.h

[mtauha]

Description of Change

Checklist

• [ ] Added description of change
• [x] Added file name matches File name guidelines
• [ ] Added tests and example, test must pass
• [ ] Added documentation so that the program is self-explanatory and educational - Doxygen guidelines
• [x] Relevant documentation/comments is changed or added
• [ ] PR title follows semantic commit guidelines
• [x] Search previous suggestions before making a new one, as yours may be a duplicate.
• [x] I acknowledge that all my contributions will be made under the project's license.

Notes:

[github-actions[bot]]

This pull request has been automatically marked as abandoned because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[github-actions[bot]]

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