Create XEP XML file

Summary:
Created XML file for XEP-0156.

URLs are provided by OpenFire administration panel.

Ref T1582.

Test Plan:

• Check individual URLs
• Lint XML

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1582

Differential Revision: https://devcentral.nasqueron.org/D3436