Few grammar errors on comments framework example page
|Reported by:||Owned by:||nobody|
|Cc:||Triage Stage:||Ready for checkin|
|Has patch:||yes||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
On https://docs.djangoproject.com/en/dev/ref/contrib/comments/example/, instances of it's should be replaced with its. Also, in-built should be replaced with built-in.