Improve download from stream example (#26384)

aspnetcore/blazor/file-downloads.md

@@ -76,6 +76,20 @@ The following example component:
 
 :::code language="razor" source="~/../blazor-samples/6.0/BlazorSample_WebAssembly/Pages/file-downloads/FileDownload1.razor":::
 
+For a component in a Blazor Server app that must return a <xref:System.IO.Stream> for a physical file, the component can call <xref:System.IO.File.OpenRead%2A?displayProperty=nameWithType>, as the following example demonstrates:
+
+```csharp
+private Stream GetFileStream()
+{
+    return File.OpenRead(@"{PATH}");
+}
+```
+
+In the preceding example, the `{PATH}` placeholder is the path to the file. The `@` prefix indicates that the string is a [*verbatim string literal*](/dotnet/csharp/programming-guide/strings/#verbatim-string-literals), which permits the use of backslashes (`\`) in a Windows OS path and embedded double-quotes (`""`) for a single quote in the path. Alternatively, avoid the string literal (`@`) and use either of the following approaches:
+
+* Use escaped backslashes (`\\`) and quotes (`\"`).
+* Use forward slashes (`/`) in the path, which are supported across platforms in ASP.NET Core apps, and escaped quotes (`\"`).
+
 ## Download from a URL
 
 *This section applies to files that are relatively large, typically 250 MB or larger.*