Adding base add package sub command

src/dotnet/commands/dotnet-add/dotnet-add-package/LocalizableStrings.cs

@@ -0,0 +1,22 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace Microsoft.DotNet.Tools.Add.PackageReference
+{
+    internal class LocalizableStrings
+    {
+        public const string AppFullName = ".NET Add Package reference Command";
+
+        public const string AppDescription = "Command to add package reference";
+
+        public const string AppHelpText = "Package references to add";
+
+        public const string CmdFrameworkDescription = "Add reference only when targetting a specific framework";
+
+        public const string CmdNoRestoreDescription = "Add reference without performing restore preview and compatibility check.";
+
+        public const string CmdSourceDescription = "Use specific NuGet package sources to use during the restore.";
+
+        public const string CmdPackageDirectoryDescription = "Restore the packages to this Directory .";
+    }
+}