Remove array element

---

examples/mongodb/remove_array_element.txt

> db.users.update({ name: "Zorg" },
         { $pull : { kids : { name : "Joe" } } })

> db.users.find()
{ "_id" : ObjectId("526b8fdba444e81f1ca06ba2"), "name" : "Foo" }
{ "_id" : ObjectId("526b9048a444e81f1ca06ba3"), "name" : "Zorg",
     "kids" : [ { "name" : "Mary" } ] }
{ "_id" : ObjectId("526ba048a444e81f1ca06ba4"), "name" : "Moo" }