I am trying to upload a Excel document (.xls) file to a page within my space in confluence via the Cloud Rest API. However, we are not trying to upload it as an attachment. We want the file to be uploaded to the page itself.
The following command uploads it to the page as an attachment:
curl.exe -v -S -u username:password -X POST -H "X-Atlassian-Token: no-check;" "file=@<path to file>" "https://<environment>/wiki/rest/api/content/<page>/child/attachment"
This is not what we want. Below is a picture of a page with the file upload manually. This is what we are looking for via the rest API.

This is what we are getting from the above command:
They get attached to the attachments.