Add Payhawk.com VDP

[miglen]

Summary

Adding payhawk.com/security/disclosure program.

Quality Assurance Checklist

Review Items	Y/N
Site has a publicly known bug bounty or vulnerability disclosure program	Y
Disclosure policy is publicly available	Y
Public URL	Y
Submission follows the Diodb schema	Y

Your Twitter handle (Optional): @miglen

[nikitastupin]

Thank you!