Copyright notice + "Powered by Wiki.js" should appear on print layout

[justinacolmena]

Describe the bug
The copyright notice is missing from the print layout.

To Reproduce

1. Go to a page on your wiki.js
2. Click on the printer icon (located with "bookmark" and "share") below "table of contents", "tags", and "last edited by".
3. Scroll down to bottom of last page of print layout.
4. There is no copyright notice
   Expected behavior
   Should see the usual line that reads:

© 2020 [My Organization]. All rights reserved. | Powered by Wiki.js

Host Info (please complete the following information):

• OS: Linux - Centos (core) 7.7.1908 x64
• Wiki.js version: 2.1.113
• Database engine: PostgreSQL 12.2

Additional context
The "Body HTML Injection" from the Administration "Theme" area ("Code Injection") does appear at the bottom of the page in print layout, by default, whether or not this is intended. I know that essentially all these options are adjustable by CSS override, but I would personally want the "print layout" CSS needs to be plain, efficient, and readable as a paper document, and to include, by default, the copyright line and otherwise as little as possible beyond the actual content of the article.

I am not a copyright freak or a music monster, but the notice is very important to some people, and should also appear on the page in printed form.