Fix typo.

src/pages/learn/execution.mdx

@@ -129,7 +129,7 @@ This is an example of _scalar coercion_. The type system knows what to expect an
 We've already seen some of what happens when a field returns a list of things with the `appearsIn` field above. It returned a [List type](/learn/schema/#lists) containing Enum type values, and since that's what the type system expected, each item in the list was coerced to the appropriate value. What happens when the `starships` field is resolved?
 
 ```js
-functio Human_starships (obj, args, context, info) {
+function Human_starships (obj, args, context, info) {
   return obj.starshipIDs.map(
     id => context.db.loadStarshipByID(id).then(
       shipData => new Starship(shipData)