Fix missing tag in example code

Author: Sorita Heng

modules/ROOT/partials/integrations/blazor-postinstall.adoc

@@ -55,7 +55,7 @@ _File:_ `+Pages/Index.razor+`
 @using TinyMCE.Blazor
 
 <h1>Hello, world!</h1>
-Welcome to your new app.
+<h2>Welcome to your new app.</h2>
 <Editor />
 ----
 * Using the component with its namespace: 
@@ -76,7 +76,7 @@ _File:_ `+Pages/Index.razor+`
 @using TinyMCE.Blazor
 
 <h1>Hello, world!</h1>
-Welcome to your new app.
+<h2>Welcome to your new app.</h2>
 <Editor />
 ---- 
 +