Track inclusion of ISRG root

[FranklinYu]

This forum post suggest tracking inclusion of ISRG root certificate. Currently IdenTrust certificate is already included in several trust store, but it would be cool if this is tracked somewhere. The forum post suggested we document (track) it in

https://letsencrypt.org/certificates/

But I would also consider

https://letsencrypt.org/docs/certificate-compatibility/

[tdelmas]

Another useful thread on the subject: https://community.letsencrypt.org/t/browser-os-vendors-with-isrg-root-in-their-root-certificate-stores/28900