[INT-6508] ATS Bullhorn Assess/BG Check T2 Doc Improvements

[sourabh-stackone]

Context

---

Summary by cubic

Clarifies Bullhorn Assessment/Background Check docs to match Bullhorn UI and webhook flow. Addresses INT-6508 by making the T2 guide clearer and easier to follow.

• Refactors
  • Updated wording from “test notifications” to “webhook notifications.”
  • Unified terminology: “Assessment or Background Check” tab/button and steps.
  • Streamlined steps for sending invitations and checking results (including Pending status and score).
  • Grammar and clarity fixes for concise, consistent instructions.

[Copilot]

Pull Request Overview

This PR improves the documentation for Bullhorn Assessment and Background Check integration by updating terminology and enhancing clarity throughout the content.

• Updated language to be more consistent and generic, changing specific "background check" references to "assessment or background check"
• Improved grammar and sentence structure for better readability
• Enhanced step titles and descriptions to be more descriptive and user-friendly

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}