Add -Not Feature to Where-Object (#2292)

Fix #2199

Author: SimonWahlin

reference/6/Microsoft.PowerShell.Core/Where-Object.md

@@ -21,6 +21,11 @@ Selects objects from a collection based on their property values.
 Where-Object [-InputObject <PSObject>] [-Property] <String> [[-Value] <Object>] [-EQ] [<CommonParameters>]
 ```
 
+### NotSet
+```
+Where-Object [-Property] <string> -Not [-InputObject <psobject>] [<CommonParameters>]
+```
+
 ### ScriptBlockSet
 
 ```
@@ -925,6 +930,25 @@ Accept pipeline input: False
 Accept wildcard characters: False
 ```
 
+### -Not
+Indicates that this cmdlet gets objects if the property does not exist or has a value of null or false.
+
+For example: `Get-Service | where -Not "DependentServices"`
+
+This parameter was introduced in Windows PowerShell 6.1.
+
+```yaml
+Type: SwitchParameter
+Parameter Sets: Not
+Aliases: 
+
+Required: True
+Position: Named
+Default value: None
+Accept pipeline input: False
+Accept wildcard characters: False
+```
+
 ### -NotContains
 
 Indicates that this cmdlet gets objects if none of the items in the property value is an exact match for the specified value.