graph2: Added move mutation to chapter.

graph2/schema/types/Chapter.gql

@@ -61,6 +61,15 @@ input ChapterEditInput {
   clearFictionalDate: Boolean
 }
 
+# Input for moveChapter mutation
+input ChapterMoveInput {
+  # The chapter to move
+  id: String!
+
+  # The story to move it to
+  storyId: String!
+}
+
 # Input for removeChapter mutation
 input ChapterRemoveInput {
   # The chapter to remove