Bumped version from 1.0 to 2.0 (#4242)

Author: vanillajonathan

aspnetcore/tutorials/dotnet-watch.md

@@ -47,7 +47,7 @@ Navigate to the product API (`http://localhost:5000/api/math/product?a=4&b=5`),
 - Add `Microsoft.DotNet.Watcher.Tools` to the *.csproj* file:
  ```xml
  <ItemGroup>
-   <DotNetCliToolReference Include="Microsoft.DotNet.Watcher.Tools" Version="1.0.0" />
+   <DotNetCliToolReference Include="Microsoft.DotNet.Watcher.Tools" Version="2.0.0" />
  </ItemGroup> 
  ```