Add a missing feature gate entry

The `EnableAggregatedDiscoveryTimeout` (deprecated) is not listed in the
second table. This PR adds it back.

Author: tengqm

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

@@ -242,6 +242,7 @@ different Kubernetes components.
 | `DynamicProvisioningScheduling` | - | Deprecated| 1.12 | - |
 | `DynamicVolumeProvisioning` | `true` | Alpha | 1.3 | 1.7 |
 | `DynamicVolumeProvisioning` | `true` | GA | 1.8 | - |
+| `EnableAggregatedDiscoveryTimeout` | `true` | Deprecated | 1.16 | - |
 | `EnableEquivalenceClassCache` | `false` | Alpha | 1.8 | 1.14 |
 | `EnableEquivalenceClassCache` | - | Deprecated | 1.15 | - |
 | `ExperimentalCriticalPodAnnotation` | `false` | Alpha | 1.5 | 1.12 |