[doc] Update backend api doc

The some of the commands described here were for the V1 API.
2 jobs for 70_zmq_architecture_documentation in 18 minutes and 50 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #160020
docker-build
build_linux_36

00:11:54

64.0%
passed #160021
macosx
build_macosx_36

00:18:50

64.0%