Rename network-plugin-dir kubelet flag to cni-bin-dir (#7224)

docs/concepts/cluster-administration/network-plugins.md

@@ -20,8 +20,8 @@ Network plugins in Kubernetes come in a few flavors:
 
 The kubelet has a single default network plugin, and a default network common to the entire cluster. It probes for plugins when it starts up, remembers what it found, and executes the selected plugin at appropriate times in the pod lifecycle (this is only true for Docker, as rkt manages its own CNI plugins). There are two Kubelet command line parameters to keep in mind when using plugins:
 
-* `network-plugin-dir`: Kubelet probes this directory for plugins on startup
-* `network-plugin`: The network plugin to use from `network-plugin-dir`.  It must match the name reported by a plugin probed from the plugin directory.  For CNI plugins, this is simply "cni".
+* `cni-bin-dir`: Kubelet probes this directory for plugins on startup
+* `network-plugin`: The network plugin to use from `cni-bin-dir`.  It must match the name reported by a plugin probed from the plugin directory.  For CNI plugins, this is simply "cni".
 
 ## Network Plugin Requirements
 
@@ -47,7 +47,7 @@ Kubenet creates a Linux bridge named `cbr0` and creates a veth pair for each pod
 
 The plugin requires a few things:
 
-* The standard CNI `bridge`, `lo` and `host-local` plugins are required, at minimum version 0.2.0. Kubenet will first search for them in `/opt/cni/bin`. Specify `network-plugin-dir` to supply additional search path. The first found match will take effect.
+* The standard CNI `bridge`, `lo` and `host-local` plugins are required, at minimum version 0.2.0. Kubenet will first search for them in `/opt/cni/bin`. Specify `cni-bin-dir` to supply additional search path. The first found match will take effect.
 * Kubelet must be run with the `--network-plugin=kubenet` argument to enable the plugin
 * Kubelet should also be run with the `--non-masquerade-cidr=<clusterCidr>` argument to ensure traffic to IPs outside this range will use IP masquerade.
 * The node must be assigned an IP subnet through either the `--pod-cidr` kubelet command-line option or the `--allocate-node-cidrs=true --cluster-cidr=<cidr>` controller-manager command-line options.
@@ -69,5 +69,5 @@ This option is provided to the network-plugin; currently **only kubenet supports
 ## Usage Summary
 
 * `--network-plugin=cni` specifies that we use the `cni` network plugin with actual CNI plugin binaries located in `--cni-bin-dir` (default `/opt/cni/bin`) and CNI plugin configuration located in `--cni-conf-dir` (default `/etc/cni/net.d`).
-* `--network-plugin=kubenet` specifies that we use the `kubenet` network plugin with CNI `bridge` and `host-local` plugins placed in `/opt/cni/bin` or `network-plugin-dir`.
+* `--network-plugin=kubenet` specifies that we use the `kubenet` network plugin with CNI `bridge` and `host-local` plugins placed in `/opt/cni/bin` or `cni-bin-dir`.
 * `--network-plugin-mtu=9001` specifies the MTU to use, currently only used by the `kubenet` network plugin.