Update .natvis messaging with showDisplayString

Author: pieandcakes

launch.md

@@ -29,6 +29,7 @@ Set or change the following options to control VS Code's behavior during debuggi
   * **traceResponse**: Optional flag to determine whether diagnostic adapter command and response tracing should be logged to the Debug Console. Defaults to false.
 
 **visualizerFile**: .natvis file to be used when debugging. See [Natvis syntax reference](http://aka.ms/natvis#Anchor_8) for information on how to create natvis files.
+**showDisplayString**: When a visualizerFile is specified, showDisplayString will enable the display string. Turning this option on can cause slower performance during debugging.
 
 **Example:**
 
@@ -44,7 +45,8 @@ Set or change the following options to control VS Code's behavior during debuggi
        "moduleLoad": false,
        "trace": true
     },
-   "visualizerFile": "${workspaceRoot}/my.natvis"
+   "visualizerFile": "${workspaceRoot}/my.natvis",
+   "showDisplayString": "true"
 }
 ```