Improve interface docstrings
Improve interface docstrings

wteiken/letsencrypt,TheBoegl/letsencrypt,wteiken/letsencrypt,jtl999/certbot,jtl999/certbot,dietsche/letsencrypt,DavidGarciaCat/letsencrypt,lmcro/letsencrypt,mitnk/letsencrypt,jsha/letsencrypt,brentdax/letsencrypt,brentdax/letsencrypt,mitnk/letsencrypt,lmcro/letsencrypt,dietsche/letsencrypt,thanatos/lets-encrypt-preview,bsmr-misc-forks/letsencrypt,letsencrypt/letsencrypt,jsha/letsencrypt,letsencrypt/letsencrypt,thanatos/lets-encrypt-preview,stweil/letsencrypt,DavidGarciaCat/letsencrypt,TheBoegl/letsencrypt,stweil/letsencrypt,bsmr-misc-forks/letsencrypt