Deebster, 1 year ago

This is probably too late to be useful, but what's on markdownguide.org works:

1. First item
2. Second item
3. Third item
   • Indented item
   • Indented item
4. Fourth item

Or

1. First item
2. Second item
3. Third item
   1. Indented item
   2. Indented item
4. Fourth item

It's not 1a, but it is how you do sublists.