How to automatically create ordered lists in Vim

Your start with something like this

one
two
three

Use the VISUAL BLOCK mode and Shift-i to add numbers

0. one
0. two
0. three

Select in VISUAL LINE mode, then you can increment by 1 with Ctrl-a

1. one
1. two
1. three

Note that this would already be correctly rendered when converted from Markdown to HTML.

Or you can press g Ctrl-a to order the lines in the text file

1. one
2. two
3. three

Instead of Ctrl-a, you can decrement by pressing Ctrl-x.

# before 
1. one
2. two
3. three

# after
0. one
0. two
0. three