Update String.xml

Author: gewarren

xml/System/String.xml

@@ -124,7 +124,7 @@
     </Attribute>
   </Attributes>
   <Docs>
-    <summary>Represents text as a sequence of UTF-16 code units.</summary>
+    <summary>Represents text as a sequence of UTF-16 code units.Test</summary>
     <remarks>For more information about this API, see <see href="/dotnet/fundamentals/runtime-libraries/system-string">Supplemental API remarks for String</see>.</remarks>
     <related type="ExternalDocumentation" href="https://www.microsoft.com/download/details.aspx?id=10921">Sorting Weight Tables for Windows (.NET Framework and .NET Core only)</related>
     <related type="ExternalDocumentation" href="https://www.unicode.org/Public/UCA/latest/allkeys.txt">Default Unicode Collation Element Tables</related>