feature request: watch with devtools (aka "hot reload")

[gigaga]

Context:

• version (md-to-pdf -v): 2.8.2
• platform (Unix, macOS, Windows): Windows
• node version: 10.15.3

Describe the bug:

I'd like to run watch mode with devtools to be able to see the render in Chrome in live but it does not work --> Changes are not displayed

[simonhaenisch]

In its current state, --watch cannot work with --devtools because the file watcher only kicks in after the first conversion has finished. Even if that was "fixed", it would create a new browser tab each time you make a change. It's technically possible to hot-reload the whole page though (by replacing its content), so I'll leave this open as a feature request. I don't have any capacity to implement this though, as I'm focusing on other stuff in the v3 branch at the moment.