Battle Axe - Tappara.co冰球社区的免费主题

I am just starting to look at 1.8 and it seems that the whole Customization has been dramatically changed.

Is there any documentation on how are the 1.7 customizations managed by the upgrade process and what should be taken into account prior to the upgrade?

Our overall customization is made of multiple several code snippets, impacting different parts of the UI.