HTTP is not used for RPKI information, the RTR protocol is used, which works on
top of plain TCP. Although some implementations can use TLS, VyOS (and FRR) do
not support it, and use either plain TCP or SSH.
I took the remark that rpki.readthedocs.io is somewhat NLnet Labs tools-centric to
heart and made it completely neutral. It no longer has any vendor-specific
documentation at all.