Make workhorse assisted uploads mandatory in REST API documentation

Summary

Update the Workhorse assisted uploads documentation to make workhorse assisted uploads mandatory for all content type parameters in the REST API, rather than merely suggested.

Proposal

Update the documentation to:

• Change language from "should use" to "must use" workhorse assisted uploads
• Clearly state this is a mandatory requirement for all new REST API endpoints accepting content type parameters
• Explain the benefits of this approach (handling large files, avoiding timeouts, etc.)
• Include examples of correct implementation