added entity for sub category model

[octocamocoder47]

Description
added entity for sub category model

This PR fixes #377

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[leecalcote]

Thank you, @octocamocoder47 👍

This is a positive step. Will you confirm that you used https://github.com/oapi-codegen/oapi-codegen to generate this?

If still wasn't used, will you generate with this tool, please?

[octocamocoder47]

Thank you @leecalcote for acknowledgment.

I didn't used the above mentioned tool.
I will use above tool and modify the pr.

[fitzergerald]

Good work so far!