Fill some description tags in Vector2.js. Fixed some descriptions.
Fill some description tags in Vector2.js. Fixed some descriptions.

Filled for:
setFromObject
constructor

rblopes/phaser,TukekeSoft/phaser,englercj/phaser,pixelpicosean/phaser,mahill/phaser,BeanSeed/phaser,TukekeSoft/phaser,spayton/phaser,BeanSeed/phaser,photonstorm/phaser,photonstorm/phaser,mahill/phaser,TukekeSoft/phaser,spayton/phaser