feat(vue-app): rename transition to pageTransition and deprecate it

[atinux]

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

Following this tweet: https://twitter.com/Atinux/status/1118789460253184000?s=19
Since we have layoutTransition, it makes more sense to rename transition to pageTransition in nuxt.config.js

I also added a warning for those using transition in order to rename it:

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly. (PR: #)
• I have added tests to cover my changes (if not applicable, please state why)
• All new and existing tests are passing.

[kevinmarrec]

Unit tests seems to be failing, you probably need to change few other things to fix them 😁

unit tests fixed