DDSaaS: ServiceNow Performance Update

[akaila-crest]

What does this PR do?

This PR makes a change to the ServiceNow Performance Integration README file and the documentation reference link.

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• [ ] If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[cit-pr-commenter[bot]]

PR Security Update

All commits in this PR up to and including 9754d70 have been reviewed and marked safe by SDLC security. For any questions, please reach out to #ci-for-external-contributors-collab on Slack.