Updated NuGet package version in docs

Co-authored-by: Michael Hawker MSFT (XAML Llama) <[email protected]>

Author: Sergio0694

docs/mvvm/MigratingFromMvvmLight.md

@@ -22,13 +22,13 @@ To take advantage of the Windows Community Toolkit MVVM framework, you'll first
 ### Install via .NET CLI
 
 ```
-dotnet add package Microsoft.Toolkit.Mvvm --version x.x.x
+dotnet add package Microsoft.Toolkit.Mvvm --version 7.0.0
 ```
 
 ### Install via PackageReference
 
 ```xml
-<PackageReference Include="Microsoft.Toolkit.Mvvm" Version="x.x.x" />
+<PackageReference Include="Microsoft.Toolkit.Mvvm" Version="7.0.0" />
 ```
 
 ## Migrating ObservableObject
@@ -804,4 +804,4 @@ The following components and their associated helpers/extension methods do not h
 
 - Empty
 - WeakAction
-- WeakFunc
+- WeakFunc