Add topic with example about property_upload

[diana-lakatos]

We need a topic that explains property_upload and the two new additions: how to set content disposition and content type for property_upload .

What we have so far:
https://documentation.platformos.com/api-reference/graphql/propertyupload.html
https://documentation.platformos.com/api-reference/graphql/propertiesinterface.html#L52

[richxrich]

👍

[pavelloz]

Inspiration, as it uses property_upload:

Tutorial: https://documentation.platformos.com/developer-guide/user-uploads/uploading-files-directly-amazons3-using-uppy
Example: https://examples.platform-os.com/direct-s3-upload/images

[diana-lakatos]

Task: check if our documentation includes everything