kube-proxy disclaimer about cleanup (#28147)

* kube-proxy disclaimer about cleanup

* Update content/en/docs/concepts/services-networking/service.md

Co-authored-by: Tim Bannister <tim@scalefactory.com>

* Update content/en/docs/concepts/services-networking/service.md

Co-authored-by: Tim Bannister <tim@scalefactory.com>

* kube-proxy config note

* Update service.md

kube proxy configuration

Co-authored-by: Tim Bannister <tim@scalefactory.com>

content/en/docs/concepts/services-networking/service.md

@@ -242,9 +242,25 @@ There are a few reasons for using proxying for Services:
   on the DNS records could impose a high load on DNS that then becomes
   difficult to manage.
 
+Later in this page you can read about various kube-proxy implementations work. Overall,
+you should note that, when running `kube-proxy`, kernel level rules may be
+modified (for example, iptables rules might get created), which won't get cleaned up, 
+in some cases until you reboot.  Thus, running kube-proxy is something that should
+only be done by an administrator which understands the consequences of having a
+low level, privileged network proxying service on a computer.  Although the `kube-proxy`
+executable supports a `cleanup` function, this function is not an official feature and
+thus is only available to use as-is.
+
+### Configuration
+
+Note that the kube-proxy starts up in different modes, which are determined by its configuration.
+- The kube-proxy's configuration is done via a ConfigMap, and the ConfigMap for kube-proxy effectively deprecates the behaviour for almost all of the flags for the kube-proxy.
+- The ConfigMap for the kube-proxy does not support live reloading of configuration.
+- The ConfigMap parameters for the kube-proxy cannot all be validated and verified on startup.  For example, if your operating system doesn't allow you to run iptables commands, the standard kernel kube-proxy implementation will not work.  Likewise, if you have an operating system which doesn't support `netsh`, it will not run in Windows userspace mode.
+
 ### User space proxy mode {#proxy-mode-userspace}
 
-In this mode, kube-proxy watches the Kubernetes control plane for the addition and
+In this (legacy) mode, kube-proxy watches the Kubernetes control plane for the addition and
 removal of Service and Endpoint objects. For each Service it opens a
 port (randomly chosen) on the local node.  Any connections to this "proxy port"
 are proxied to one of the Service's backend Pods (as reported via