Update docs to reflect new -Subsystem parameter (#2339)

* update docs to reflect new -Subsystem for PSSession cmdlets

* address Paul's feedback

Author: SteveL-MSFT

reference/6/Microsoft.PowerShell.Core/Enter-PSSession.md

@@ -69,7 +69,7 @@ Enter-PSSession -ContainerId <String> [-ConfigurationName <String>] [-RunAsAdmin
 ### HostName
 ```
 Enter-PSSession [-HostName] <string> [-Port <int>] [-UserName <string>] [-KeyFilePath <string>] [-SSHTransport]
- [-ConfigurationName <String>] [<CommonParameters>]
+ [-Subsystem <String>] [<CommonParameters>]
 ```
 
 ## DESCRIPTION
@@ -317,7 +317,7 @@ For more information, see about_Preference_Variables.
 
 ```yaml
 Type: String
-Parameter Sets: ComputerName, Uri, VMId, VMName, ContainerId, HostName
+Parameter Sets: ComputerName, Uri, VMId, VMName, ContainerId
 Aliases:
 
 Required: False
@@ -629,6 +629,27 @@ Accept pipeline input: False
 Accept wildcard characters: False
 ```
 
+### -Subsystem
+Specifies the SSH subsystem used for the new **PSSession**.
+
+This specifies the subsystem to use on the target as defined in sshd_config.
+The subsystem starts a specific version of PowerShell with predefined parameters.
+If the specified subsystem does not exist on the remote computer, the command fails.
+
+If this parameter is not used, the default is the 'powershell' subsystem.
+
+```yaml
+Type: String
+Parameter Sets: HostName
+Aliases:
+
+Required: False
+Position: Named
+Default value: powershell
+Accept pipeline input: True (ByPropertyName)
+Accept wildcard characters: False
+```
+
 ### -UserName
 Specifies the user name for the account used to create a session on the remote computer. User authentication method will depend on how Secure Shell (SSH) is configured on the remote computer.
 

reference/6/Microsoft.PowerShell.Core/Invoke-Command.md

@@ -116,7 +116,7 @@ Invoke-Command [-ConfigurationName <String>] [-ThrottleLimit <Int32>] [-AsJob] [
 
 ### HostName
 ```
-Invoke-Command [-ConfigurationName <String>] -ScriptBlock <scriptblock> -HostName <string[]> [-Port <int>]
+Invoke-Command [-Subsystem <String>] -ScriptBlock <scriptblock> -HostName <string[]> [-Port <int>]
  [-AsJob] [-HideComputerName] [-UserName <string>] [-KeyFilePath <string>] [-SSHTransport] [-RemoteDebug]
  [-InputObject <psobject>] [-ArgumentList <Object[]>] [<CommonParameters>]
 ```
@@ -715,7 +715,7 @@ For more information, see about_Preference_Variables.
 
 ```yaml
 Type: String
-Parameter Sets: ComputerName, FilePathComputerName, Uri, FilePathUri, VMId, VMName, FilePathVMId, FilePathVMName, ContainerId, FilePathContainerId, HostName
+Parameter Sets: ComputerName, FilePathComputerName, Uri, FilePathUri, VMId, VMName, FilePathVMId, FilePathVMName, ContainerId, FilePathContainerId
 Aliases:
 
 Required: False
@@ -1228,6 +1228,27 @@ Accept pipeline input: False
 Accept wildcard characters: False
 ```
 
+### -Subsystem
+Specifies the SSH subsystem used for the new **PSSession**.
+
+This specifies the subsystem to use on the target as defined in sshd_config.
+The subsystem starts a specific version of PowerShell with predefined parameters.
+If the specified subsystem does not exist on the remote computer, the command fails.
+
+If this parameter is not used, the default is the 'powershell' subsystem.
+
+```yaml
+Type: String
+Parameter Sets: HostName
+Aliases:
+
+Required: False
+Position: Named
+Default value: powershell
+Accept pipeline input: True (ByPropertyName)
+Accept wildcard characters: False
+```
+
 ### -UserName
 Specifies the user name for the account used to run a command on the remote computer. User authentication method will depend on how Secure Shell (SSH) is configured on the remote computer.
 

reference/6/Microsoft.PowerShell.Core/New-PSSession.md

@@ -58,7 +58,7 @@ New-PSSession [-Name <String[]>] [-ConfigurationName <String>] -ContainerId <Str
 ### HostName
 ```
 New-PSSession [-HostName] <string[]> [-Name <string[]>] [-Port <int>] [-UserName <string>] [-KeyFilePath <string>
- [-ConfigurationName <String>] [-SSHTransport] [<CommonParameters>]
+ [-Subsystem <String>] [-SSHTransport] [<CommonParameters>]
 ```
 
 ### SSHConnection
@@ -380,7 +380,7 @@ For more information, see [about_Preference_Variables](About/about_Preference_Va
 
 ```yaml
 Type: String
-Parameter Sets: ComputerName, VMName, Uri, VMId, ContainerId, HostName
+Parameter Sets: ComputerName, VMName, Uri, VMId, ContainerId
 Aliases:
 
 Required: False
@@ -800,6 +800,27 @@ Accept pipeline input: False
 Accept wildcard characters: False
 ```
 
+### -Subsystem
+Specifies the SSH subsystem used for the new **PSSession**.
+
+This specifies the subsystem to use on the target as defined in sshd_config.
+The subsystem starts a specific version of PowerShell with predefined parameters.
+If the specified subsystem does not exist on the remote computer, the command fails.
+
+If this parameter is not used, the default is the 'powershell' subsystem.
+
+```yaml
+Type: String
+Parameter Sets: HostName
+Aliases:
+
+Required: False
+Position: Named
+Default value: powershell
+Accept pipeline input: True (ByPropertyName)
+Accept wildcard characters: False
+```
+
 ### CommonParameters
 This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable, -InformationAction, -InformationVariable, -OutVariable, -OutBuffer, -PipelineVariable, -Verbose, -WarningAction, and -WarningVariable. For more information, see about_CommonParameters (http://go.microsoft.com/fwlink/?LinkID=113216).