feat: add Requesting App to XAA docs

[lrzhou25]

Description

References

Testing

Checklist

• I've read and followed CONTRIBUTING.md.
• I've tested the site build for this change locally.
• I've made appropriate docs updates for any code or config changes.
• I've coordinated with the Product Docs and/or Docs Management team about non-trivial changes.

[github-actions]

Summary

Status	Count
🔍 Total	36
✅ Successful	6
⏳ Timeouts	0
🔀 Redirected	0
👻 Excluded	29
❓ Unknown	0
🚫 Errors	1
⛔ Unsupported	0

Errors per input

Errors in main/docs/secure/call-apis-on-users-behalf/xaa/set-up-resource-app.mdx

• [ERROR] https://developer.okta.com/docs/guides/submit-app-overview/#submission-process-for-sso-and-scim-integrations | Cannot find fragment: Fragment not found in document. Check if fragment exists or page structure
  Full Github Actions output