Docs: InputOf operator example

Decoder.md

@@ -349,7 +349,7 @@ console.log(isRight(NumberFromString.decode('a'))) // => false
 
 # Extracting static types from decoders
 
-Static types can be extracted from decoders using the `TypeOf` operator
+Static types can be extracted from decoders using the `TypeOf` and `InputOf` operators
 
 ```ts
 export const Person = D.type({
@@ -364,6 +364,11 @@ type Person = {
     age: number;
 }
 */
+
+type PersonInputType = D.InputOf<typeof Person>
+/*
+type PersonInputType = unknown
+*/
 ```
 
 Note that you can define an `interface` instead of a type alias