Mark WarningHeader feature gate as GA

Author: liggitt

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

@@ -180,7 +180,6 @@ different Kubernetes components.
 | `ValidateProxyRedirects` | `false` | Alpha | 1.12 | 1.13 |
 | `ValidateProxyRedirects` | `true` | Beta | 1.14 | |
 | `VolumeCapacityPriority` | `false` | Alpha | 1.21 | - |
-| `WarningHeaders` | `true` | Beta | 1.19 | |
 | `WinDSR` | `false` | Alpha | 1.14 | |
 | `WinOverlay` | `false` | Alpha | 1.14 | 1.19 |
 | `WinOverlay` | `true` | Beta | 1.20 | |
@@ -386,6 +385,8 @@ different Kubernetes components.
 | `VolumeSubpathEnvExpansion` | `false` | Alpha | 1.14 | 1.14 |
 | `VolumeSubpathEnvExpansion` | `true` | Beta | 1.15 | 1.16 |
 | `VolumeSubpathEnvExpansion` | `true` | GA | 1.17 | - |
+| `WarningHeaders` | `true` | Beta | 1.19 | 1.21 |
+| `WarningHeaders` | `true` | GA | 1.22 | - |
 | `WatchBookmark` | `false` | Alpha | 1.15 | 1.15 |
 | `WatchBookmark` | `true` | Beta | 1.16 | 1.16 |
 | `WatchBookmark` | `true` | GA | 1.17 | - |