fix wrong summary (#3655)

Author: mairaw

xml/Microsoft.JScript.Vsa/BaseVsaEngine.xml

@@ -677,7 +677,7 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>Gets or sets a value that indicates whether the source is compiled.</summary>
+        <summary>Gets a value that indicates whether the source is compiled.</summary>
         <value>
           <see langword="true" /> if the source is compiled; otherwise, <see langword="false" />.</value>
         <remarks>To be added.</remarks>