[2] and [3] list a few example documents for Software Architectures, you can google further and find some more.
I think reading through a few sample documents and based on the expectations at your current job, you can derive the necessary doc.
[1] https://www.amazon.com/Documenting-Software-Architectures-Be...
[2] https://projects.cecs.pdx.edu/attachments/download/3146/Soft...
[3] https://www.voa.va.gov/DocumentView.aspx?DocumentID=188