Mention math.rand for the todo ID (99designs#1489)

docs/content/getting-started.md

@@ -111,7 +111,7 @@ type Resolver struct{
 }
 ```
 
-Returning to `graph/schema.resolvers.go`, let's implement the bodies of those automatically generated resolver functions:
+Returning to `graph/schema.resolvers.go`, let's implement the bodies of those automatically generated resolver functions.  For `CreateTodo`, we'll use `math.rand` to simply return a todo with a randomly generated ID and store that in the in-memory todos list --- in a real app, you're likely to use a database or some other backend service.
 
 ```go
 func (r *mutationResolver) CreateTodo(ctx context.Context, input model.NewTodo) (*model.Todo, error) {