This is barely a templating engine. It's a concatenator.
i don't run a processing webserver, i serve HTML pages.
This is the rendering engine. That's all there is to it.
Note: each entry in the template should be unique or it's bound to have bugs. Also entries should not be substrings of one another.
For example, if you create <!--md:example.md-a-cool-thing.md--> and <!--md:example.md--> you'll run into issues.
i don't care, i don't plan to name my files wrong.