Fixed broken xref.

Author: Ron Petrusha

xml/System.Text.Json.Serialization/JsonExtensionDataAttribute.xml

@@ -52,7 +52,7 @@ If there is more than one extension property on a type, or it the property is no
       </AssemblyInfo>
       <Parameters />
       <Docs>
-        <summary>Instantiates a new instance of the <see cref="T:System.Text.Json.Serialization.JSonExtensionDataAttribute" /> class.</summary>
+        <summary>Instantiates a new instance of the <see cref="T:System.Text.Json.Serialization.JsonExtensionDataAttribute" /> class.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>