Improved guide instance.md examples (#1458)
Improved guide instance.md examples (#1458)

* Improved guide instance.md examples

- Made some examples stronger by making sure that if their corresponding statements were false, the examples would indeed pick up on it:
  * comparing integers will not highlight that they are the integers from the same location in memory
  * fixed the freeze example such that if commented it out, it would work

* Updated instance.md property getting

vuejs/vuejs.org,vuejs-vn/vuejs.org,Jinjiang/vuejs.org,vuejs/vuejs.org,vuejs-kr/kr.vuejs.org,vuejs-vn/vuejs.org,vuejs-fr/vuejs.org,vuejs-fr/vuejs.org,Jinjiang/vuejs.org,vuejs-kr/kr.vuejs.org,vuejs-id/docs