Remove unnecessary step

Author: benjie

spec/Section 3 -- Type System.md

@@ -1583,7 +1583,6 @@ Literal Value            | Variables               | Coerced Value
       characters {"__"} (two underscores).
    3. The input field must accept a type where {IsInputType(inputFieldType)}
       returns {true}.
-   4. Let {fieldSet} be a set containing {inputField}.
 3. If an Input Object references itself either directly or through referenced
    Input Objects, at least one of the fields in the chain of references must be
    either a nullable or a List type.