Update task.md

minor grammar mistake "it's original" should be "its original"

Author: wnleao

7-animation/2-css-animations/2-animate-logo-bezier-css/task.md

@@ -4,7 +4,7 @@ importance: 5
 
 # Animate the flying plane (CSS)
 
-Modify the solution of the previous task <info:task/animate-logo-css> to make the plane grow more than it's original size 400x240px (jump out), and then return to that size.
+Modify the solution of the previous task <info:task/animate-logo-css> to make the plane grow more than its original size 400x240px (jump out), and then return to that size.
 
 Here's how it should look (click on the plane):