This patch  allows kube-state-metrics to list and watch instances of
poddisruptionbudgets from the policy API group.

Increase CPU limits for small containers to not being throttled as often

the operator spec key is named "externalUrl", rather than "externalURL"

Do not error if no $._config.prometheus.rules are set

Explicitly reference values we are interesting in (jsonnet style)
instead of just following conventions (helm style)

Fix AlertmanagerMembersInconsistent rule

This commit adjusts the RBAC proxy for the node-exporter DaemonSet to
only listen on the Pod IP. It also adjusts the ports used by the
node-exporter Pod so that both containers are listening on 9100. The
actual node-exporter listens on 127.0.0.1:9100, while the RBAC proxy
listens on <PODIP>:9100. This ensures that port 9101 is not taken on
the host networking namespace.

kube-prometheus: Add documentaton to README on the Pod Anti-Affinity mixin

Update alertmanager retention documentation

contrib/kube-prometheus: Update experimental Custom Metrics adapter example