Update link to the NetworkPlugin interface (#9298)

* Update link to the NetworkPlugin interface

Link was broken during some refactoring (commit 4239882).
Change the link to reflect the new location.
This fixes Issue #9297

* Remove extra line

Somehow the fixed link was pasted at the end of the modified paragraph.
Remove it.

* Add back linebreak

I'll get this right... I swear.

content/en/docs/concepts/extend-kubernetes/compute-storage-net/network-plugins.md

@@ -33,7 +33,7 @@ The kubelet has a single default network plugin, and a default network common to
 
 ## Network Plugin Requirements
 
-Besides providing the [`NetworkPlugin` interface](https://github.com/kubernetes/kubernetes/tree/{{< param "fullversion" >}}/pkg/kubelet/network/plugins.go) to configure and clean up pod networking, the plugin may also need specific support for kube-proxy.  The iptables proxy obviously depends on iptables, and the plugin may need to ensure that container traffic is made available to iptables.  For example, if the plugin connects containers to a Linux bridge, the plugin must set the `net/bridge/bridge-nf-call-iptables` sysctl to `1` to ensure that the iptables proxy functions correctly.  If the plugin does not use a Linux bridge (but instead something like Open vSwitch or some other mechanism) it should ensure container traffic is appropriately routed for the proxy.
+Besides providing the [`NetworkPlugin` interface](https://github.com/kubernetes/kubernetes/tree/{{< param "fullversion" >}}/pkg/kubelet/dockershim/network/plugins.go) to configure and clean up pod networking, the plugin may also need specific support for kube-proxy.  The iptables proxy obviously depends on iptables, and the plugin may need to ensure that container traffic is made available to iptables.  For example, if the plugin connects containers to a Linux bridge, the plugin must set the `net/bridge/bridge-nf-call-iptables` sysctl to `1` to ensure that the iptables proxy functions correctly.  If the plugin does not use a Linux bridge (but instead something like Open vSwitch or some other mechanism) it should ensure container traffic is appropriately routed for the proxy.
 
 By default if no kubelet network plugin is specified, the `noop` plugin is used, which sets `net/bridge/bridge-nf-call-iptables=1` to ensure simple configurations (like Docker with a bridge) work correctly with the iptables proxy.