Add end date or expiry date to certificates section

[hugginsio]

Many professional certificates expire after a certain period of time and require a recertification process. Some certificates that expire include:

• All Google Cloud certificates
• All CNCF Certified Kubernetes certificates
• Many Microsoft certificates

Adding a field to capture the end date or expiry date would make it clear which certificates are up-to-date without forcing the user to go to another site to view additional certificate details.