Add missing documentation for StartingContainerCount metric [finishes
| `GardenContainerDestructionFailedDuration` | Time the rep's Garden backend took to destroy a container. Emitted after every failed container destruction. | ns |
| `RepBulkSyncDuration` | Time the cell rep took to synchronize the ActualLRPs it has claimed with its actual garden containers. Emitted periodically by each rep. | ns |
| `StalledGardenDuration` | Time the rep is waiting on its garden backend to become healthy during startup. Emitted only if garden not responsive when the rep starts up. | ns |
+| `StartingContainerCount` | Number of containers currently in a Reserved, Initializing, or Created state. Emitted periodically. | number |
| `StrandedEvacuatingActualLRPs` | Evacuating ActualLPRs that timed out during the evacuation process. Emitted when evacuation doesn't complete successful. | number |
| `UnhealthyCell` | Whether the cell has failed to pass its healthcheck against the garden backend. 0 signifies healthy, and 1 signifies unhealthy. Emitted periodically. | 0 or 1 (boolean) |
| `VolmanMountDuration` | Time volman took to mount a volume. Emitted by each rep when volumes are mounted. | ns |
