Update JsonApiReader.cs

Author: maurei

src/JsonApiDotNetCore/Formatters/JsonApiReader.cs

@@ -83,6 +83,7 @@ public Task<InputFormatterResult> ReadAsync(InputFormatterContext context)
             }
         }
 
+        /// <summary> Checks if the deserialized payload has an ID included </summary
         private bool CheckForId(object model)
         {
             if (model == null) return false;
@@ -97,6 +98,7 @@ private bool CheckForId(object model)
             return false;
         }
 
+        /// <summary> Checks if the elements in the deserialized payload have an ID included </summary
         private bool CheckForId(IList modelList)
         {
             foreach (var model in modelList)