The column-indexing toggle did not have a :status property. As a result,
the toggle command would enable the toggle but would not disable it. In
addition, the absence of :status prevented -off and -on commands from being
defined.
This commit adds a :status property so that the toggle works properly and
-off and -on commands are defined.
This commit also renames the toggle to "zero-based-column-indexing" in order to
make its purpose clearer.
* layers/+spacemacs/spacemacs-defaults/keybindings.el (column-indexing):
Add :status and rename to "zero-based-column-indexing".