[Doc EN]: transition.md, example 4, add a forgotten instructi… (#2500)

* Indent fix (Biggest update ever)

Signed-off-by: Bruno J. S. Lesieur <bruno.lesieur@gmail.com>

* Some line return for consistency

Signed-off-by: MachinisteWeb <bruno.lesieur@gmail.com>

* Align transitions.md example 4 text example with live example

Signed-off-by: MachinisteWeb <bruno.lesieur@gmail.com>

Author: MachinisteWeb

src/v2/guide/transitions.md

@@ -479,6 +479,7 @@ new Vue({
   methods: {
     beforeEnter: function (el) {
       el.style.opacity = 0
+      el.style.transformOrigin = 'left'
     },
     enter: function (el, done) {
       Velocity(el, { opacity: 1, fontSize: '1.4em' }, { duration: 300 })