Clarify DNS service discovery relationship to DNS-SD
Clarify DNS service discovery relationship to DNS-SD

It's a common misconception to call any DNS SRV record based discovery
approach "DNS-SD". The latter is a [ratified IETF standard][rfc6763]
which specifies a naming schema and lookup mechanism in order to provide
additional structured information. Prometheus only supports basic SRV
record lookups.

[rfc6763]: https://tools.ietf.org/html/rfc6763

ddfreyne/prometheus-docs,tcolgate/docs,ddfreyne/prometheus-docs,chosenken/docs,prometheus/docs,prometheus/docs,du2016/prometheus-docs,du2016/prometheus-docs,tcolgate/docs,open-falcon/open-falcon.github.io,chosenken/docs,prometheus/docs,Cepave/openfalcon.io,Cepave/openfalcon.io,chosenken/docs,Cepave/openfalcon.io,ddfreyne/prometheus-docs,du2016/prometheus-docs,open-falcon/open-falcon.github.io,open-falcon/open-falcon.github.io,ddfreyne/prometheus-docs,tcolgate/docs,chosenken/docs