1. Org

`org-plus-contrib` is now installed from org ELPA repository, you may
encounter strange behaviours from Org. In this case delete the `org`
directory in the `elpa` directory and restart Emacs.

2. Helm

`Helm` key bindings have been slightly adjusted:

- in `helm-find-files` (`SPC f f`): now `C-h` move up a directory
  and `C-l` enter the selected directory. `describe-key` command is
  available on `C-S-h`

- in other `helm` buffers ~C-h~ is used to go to the next source
  and `C-l` is the same as `RET`. `describe-key` command is also
  available on `C-S-h`.

3. Vim keys

`Y` has been remapped to `y$`, if you don't like this behavior you can
set the variable `dotspacemacs-remap-Y-to-y$` to nil in your dotfile.

4. Guide-key

`guide-key` has been replaced by `which-key`, you may encounter issues
if you have some `guide-key` custom configuration, remove any `guide-key`
configuration and check the options offered by `which-key`.

5. Bookmarks

The `bookmark` save file has been moved to the `.cache` directory, if
you have a bookmark file `~/.emacs.d/bookmarks` then you'll have to move
it to file `~/.emacs.d/.cache/bookmarks`

6. Ruby on Rails

Ruby on Rails framework has now its own layer called `ruby-on-rails`,
be sure to add this layer to your dotfile if you use it.

7. Django

Django framework has now its own layer called `django`,
be sure to add this layer to your dotfile if you use it.