Make the theme more n00b friendly about dnn-theme-bootstrap4-instant HOT 2 OPEN

Thanks @existenze

1. Customizing: I believe the released version is quite far behind the current code, which has a better webpack implementation. @ropalko could you check and probably re-release the package
2. We'll try to improve on this - often much has happened and it's quite a pain to find all the changes for documentation. We rarely update from the source, since we usually only use this for new setups and then customize so much, that we don't do this. But we'll try to improve on this ;).
3. Skin objects: I understand the need. We would welcome contributions for this :)

from dnn-theme-bootstrap4-instant.

@existenze @iJungleboy added a new release with better webpack performance and less packages

from dnn-theme-bootstrap4-instant.