Amend dynamic volume list docs

The dynamic volume list feature has been documented but the feature gate
related was not there yet.

Closes: kubernetes#9105

content/en/docs/concepts/storage/storage-limits.md

@@ -55,7 +55,9 @@ is an alpha feature that supports these services:
 - Amazon EBS
 - Google Persistent Disk
 
-To enable dynamic volume limits, use the `AttachVolumeLimit` flag.
+To enable dynamic volume limits, set the `AttachVolumeLimit`
+[feature gate](/docs/reference/command-line-tools-reference/feature-gates/)
+to True.
 
 When the dynamic volume limits feature is enabled, Kubernetes automatically
 determines the node type and supports the appropriate number of attachable

content/en/docs/reference/command-line-tools-reference/feature-gates.md

@@ -35,6 +35,7 @@ different Kubernetes components.
 | `APIListChunking` | `true` | Beta | 1.9 | |
 | `APIResponseCompression` | `false` | Alpha | 1.7 | |
 | `AppArmor` | `true` | Beta | 1.4 | |
+| `AttachVolumeLimit` | `false` | Alpha | 1.11 | |
 | `BlockVolume` | `false` | Alpha | 1.9 | |
 | `CPUManager` | `false` | Alpha | 1.8 | 1.9 |
 | `CPUManager` | `true` | Beta | 1.10 | |
@@ -149,6 +150,9 @@ Each feature gate is designed for enabling/disabling a specific feature:
 - `APIResponseCompression`: Compress the API responses for `LIST` or `GET` requests.
 - `AppArmor`: Enable AppArmor based mandatory access control on Linux nodes when using Docker.
    See [AppArmor Tutorial](/docs/tutorials/clusters/apparmor/) for more details.
+- `AttachVolumeLimit`: Enable volume plugins to report limits on number of volumes
+  that can be attached to a node.
+   See [dynamic volume limits](/docs/concepts/storage/storage-limits/#dynamic-volume-limits) for more details.
 - `BlockVolume`: Enable the definition and consumption of raw block devices in Pods.
    See [Raw Block Volume Support](/docs/concepts/storage/persistent-volumes/#raw-block-volume-support)
    for more details.