Fix important alert in single file deployment (dotnet#40160)

Author: Rageking8

docs/core/deploying/single-file/overview.md

@@ -13,7 +13,7 @@ Bundling all application-dependent files into a single binary provides an applic
 
 The size of the single file in a self-contained application is large since it includes the runtime and the framework libraries. In .NET 6, you can [publish trimmed](../trimming/trim-self-contained.md) to reduce the total size of trim-compatible applications. The single file deployment option can be combined with [ReadyToRun](../ready-to-run.md) and [Trim](../trimming/trim-self-contained.md) publish options.
 
-> [IMPORTANT]
+> [!IMPORTANT]
 > To run a single file app on Windows 7, you must use .NET Runtime 6.0.3 or later.
 
 ## Sample project file