Use mode-* to set var require-final-newline

[lukesanantonio]

This follows the documentation of mode-require-final-newline that says the local value of require-final-newline should be set to the value of the former (mode-require-final-newline). Another important thing to mention is that this will fix the issue / warning that occurs when using adoc-mode with ethan-wspace. This shouldn't change the behavior for any other users because the default value of mode-require-final-newline is true anyway.

[TobiasZawada]

You are right. The adoc tutorial and the adoc doc do not impose a newline character at the end of the text. So it should be left to the users general setting.