update help

Author: akshaysngupta

src/ResourceManager/Network/Commands.Network/help/New-AzureRmApplicationGateway.md

@@ -29,7 +29,7 @@ New-AzureRmApplicationGateway -Name <String> -ResourceGroupName <String> -Locati
  -RequestRoutingRules <System.Collections.Generic.List`1[Microsoft.Azure.Commands.Network.Models.PSApplicationGatewayRequestRoutingRule]>
  [-RedirectConfigurations <System.Collections.Generic.List`1[Microsoft.Azure.Commands.Network.Models.PSApplicationGatewayRedirectConfiguration]>]
  [-WebApplicationFirewallConfiguration <PSApplicationGatewayWebApplicationFirewallConfiguration>]
- [-Tag <Hashtable>] [-Force] [-AsJob] [-DefaultProfile <IAzureContextContainer>] [-WhatIf] [-Confirm]
+ [-EnableHttp2] [-Tag <Hashtable>] [-Force] [-AsJob] [-DefaultProfile <IAzureContextContainer>] [-WhatIf] [-Confirm]
  [<CommonParameters>]
 ```
 
@@ -174,6 +174,21 @@ Accept pipeline input: False
 Accept wildcard characters: False
 ```
 
+### -EnableHttp2
+Whether HTTP2 is enabled.
+
+```yaml
+Type: SwitchParameter
+Parameter Sets: (All)
+Aliases: 
+
+Required: False
+Position: Named
+Default value: None
+Accept pipeline input: True (ByPropertyName)
+Accept wildcard characters: False
+```
+
 ### -Force
 Forces the command to run without asking for user confirmation.