First off, thanks for all the work you've put into this extension! I really like the approach; it does almost everything I need and nothing I don't!

I've noticed some unexpected behaviour with lists. Both GitHub Flavoured and CommonMark%20.&text=Use%20any%20of%20*%20%2C%20%2B%20or,consistently%20use%20the%20same%20character.) specify that -, *, and + are all valid characters for a list, but + doesn't appear to be detected as such when using the <C-Space> shortcut to work with To Dos.

Reproduction Steps

Option 1

1. Open a new markdown file.
2. Enter + To do item on a new line.
3. In Normal mode, press <C-Space>. Note that a to do item does not get created.

Option 2

1. Open a new markdown file.
2. Enter - [ ] To do item on a new line.
3. Press enter to create a new to do item.
4. Press <C-t> to indent, and update the nested list item from - to +.
5. In Normal mode, press <C-Space>. Note that the to do item does not progress, nor does the parent task.

Hopefully this is sufficient to reproduce (and hopefully I haven't missed something obvious in the documentation!). If not, please let me know and I'd be happy to provide additional information.