doc: add guidelines for introduction of ERM support

PR-URL: #58526
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Ethan Arrowood <[email protected]>
Reviewed-By: Gerhard Stöbich <[email protected]>
Reviewed-By: Chengzhong Wu <[email protected]>
Reviewed-By: LiviaMedeiros <[email protected]>

Author: jasnell