Update guides/source/active_record_basics.md

Co-authored-by: Petrik de Heus <[email protected]>

Author: audiosupp

guides/source/active_record_basics.md

@@ -496,6 +496,7 @@ The above resulting in this SQL:
 -- Book.find_by(title: "Metaprogramming Ruby 2")
 SELECT "books".* FROM "books" WHERE "books"."title" = ? LIMIT ?  [["title", "Metaprogramming Ruby 2"], ["LIMIT", 1]]
 
+-- Book.find(42)
 SELECT "books".* FROM "books" WHERE "books"."id" = ? LIMIT ?  [["id", 42], ["LIMIT", 1]]
 ```