Removed the incorrect line

[j-perry2]

Summary

• Removed Application-restricted RESTful API - API key authentication as it is incorrect.
• Changed 'To use this access mode, use one of the following security patterns:' to reflect that there is only one security pattern.

Reviews Required

• Dev

Review Checklist

ℹ️ This section is to be filled in by the reviewer.

• I have reviewed the changes in this PR and they fill all or part of the acceptance criteria of the ticket, and the code is in a mergeable state.
• If there were infrastructure, operational, or build changes, I have made sure there is sufficient evidence that the changes will work.

[github-actions]

This branch is working on a ticket in the NHS Digital APM JIRA Project. Here's a handy link to the ticket:

SPINEDEM-4163