changelog.md: add telemetry notes
changelog.md: add telemetry notes

- breaking change: consul.rpc.query count semantics changed
- improvement: consul.rpc.queries_blocking added
hashicorp/consul,42wim/consul,hashicorp/consul,hashicorp/consul,42wim/consul,42wim/consul,hashicorp/consul,42wim/consul,42wim/consul