Add optional PDF rendering

[kamontat]

Problem/Motivation

It will be nice if we can choose pdf render from add-on config page

ref: https://www.bookstackapp.com/docs/admin/pdf-rendering/

Expected behavior

Changes PDF rendering

Actual behavior

Cannot

BookStack

PDF Rendering · BookStack

[sinclairpaul]

I'll just change it to use wkhtmltopdf in the next release, don't see the need to make it optional if it performs better for minimal size increase.

[sinclairpaul]

From testing the Alpine package doesn't work correctly for me, so will hold off on this for now.

[kamontat]

I tested for me is working.. how you install wkhtmltopdf command?

[sinclairpaul]

PR's are always welcome, at the moment I don't see this working under Alpine

[kamontat]

I not sure is it gonna work or not, I never run in local but I create PR so you might try #16

[sinclairpaul]

This still isn't working correctly for me, so will close it out for now.