Configuration page rework: remove duplication, make easier to maintain, add missing flag (#491)

* Configuration page rework
* Break flags into sections
* Adjust anchors
* Add Caution keyword
* Tweak description
* Add note about changelog containing details
* Update flag description indentation

Co-authored-by: Nate W. <4453979+nate-double-u@users.noreply.github.com>

Author: chalin

content/en/docs/v3.5/op-guide/clustering.md

@@ -487,8 +487,8 @@ When the `--proxy` flag is set, etcd runs in [proxy mode][proxy]. This proxy mod
 To setup an etcd cluster with proxies of v2 API, please read the the [clustering doc in etcd 2.3 release][clustering_etcd2].
 
 [clustering_etcd2]: https://github.com/etcd-io/etcd/blob/release-2.3/Documentation/clustering.md
-[conf-adv-client]: ../configuration/#--advertise-client-urls
-[conf-listen-client]: ../configuration/#--listen-client-urls
+[conf-adv-client]: ../configuration/#clustering
+[conf-listen-client]: ../configuration/#member
 [discovery-proto]: ../../dev-internal/discovery_protocol/
 [gateway]: ../gateway/
 [proxy]: https://github.com/etcd-io/etcd/blob/release-2.3/Documentation/proxy.md