Update test-plan.md

Co-Authored-By: Ajay Bhargav B <[email protected]>

Author: ryanbrandenburg

test-plan.md

@@ -106,7 +106,7 @@ To setup a test project to verify on you can do:
 * Completion is available for types that exist in the project (i.e. `Program`)
 * Typing `@model DateTime` prompts for completion for the `model` symbol and the `DateTime` symbol.
 
-#### C# Lightbulbs
+##### C# Lightbulbs
 * Typing `@{ var x = new HtmlString("sdf"); }`results in squiggles under `HtmlString`. Selecting `HtmlString` and pressing Ctrl+. results in a change suggestion to fully-qualify that type name as `Microsoft.AspNetCore.Html.HtmlString`. Hitting enter on that suggestion resolves the squiggles and changes the line.
 
 ##### C# Signature Help