Update copyright notice & footer (#2496)

## Description:

* Update copyright notice to "OpenFront and Contributors"

* remove the "how to play" on the footer, since that will be moved to
the death screen.

* Removed css and used tailwind instead for better mobile support


Describe the PR.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

src/client/styles.css

@@ -5,7 +5,6 @@
 @import url("./styles/core/variables.css");
 @import url("./styles/core/typography.css");
 @import url("./styles/layout/header.css");
-@import url("./styles/layout/footer.css");
 @import url("./styles/layout/container.css");
 @import url("./styles/components/button.css");
 @import url("./styles/components/modal.css");