Update GraphQLError constructor docs (graphql#494)

* Update GraphQLError constructor in the docs to include the 'originalError' and 'extensions' properties.

* Remove package-lock.json file that I accidentally committed.

* Add commas.

Author: ericapisani

site/graphql-js/APIReference-Errors.md

@@ -55,7 +55,9 @@ class GraphQLError extends Error {
    nodes?: Array<any>,
    stack?: ?string,
    source?: Source,
-   positions?: Array<number>
+   positions?: Array<number>,
+   originalError?: ?Error,
+   extensions?: ?{ [key: string]: mixed }
  )
 }
 ```