Doc: parent config has more features than balancer plugin

The balancer plugin has consistent hashing, and round robin
(not weighted). As a remap plugin, it is limited to url attribnutes.
It neither has passive nor active health checks.

Really, Balancer plugin should be deprecated.

(cherry picked from commit 2f55f4bf6a8bbfd615d7517f503b0517ed647143)
2 files changed