docs(ngAnimate): fixed two small typos
docs(ngAnimate): fixed two small typos

Line 162: 'defiend' should be 'defined'
Line 225: 'callback function be excuted' should be 'callback function will be executed'.

Closes #5048

ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js