Allow customization of stylesheets by projects using Spring Doc Resources

[odrotbohm]

We occasionally need to tweak a few of the CSS declared in spring.css and Asciidoctor unfortunately doesn't seem to have a solution to using multiple CSS files. I wonder if it was possible if the project here would out of the box include an additional, empty CSS file. Consuming projects could then override those custom CSS declarations by maintaining a file named as the empty one and just copy theirs over the one produced by Spring Doc Resources.

[odrotbohm]

This doesn't seem to be necessary. I've resorted to the following strategy to make customizations:

• Keep a custom stylesheet foobar.css and let the Asciidoctor plugin use that
• Make sure this ends up next to spring.css
• Have an @import "spring.css" at the very top of the former to load the declarations there