Revise Why Use Markdown section to mention ability to diff

[mattcone]

Received via email:

One additional point to the topic 'Why Use Markdown?' with the context 'why people use Markdown instead of a WYSIWYG editor'. An additional reason is that is comparable with a diff tool (based on text). Maybe you want add this as well, imho it is important too.

[mischlrebl]

thanks for that!

and therefore it can be managed in a version control system like Git to track changes over the time