Update dates for 2024

[gitlankford]

Various pages look out of date, particularly the Contribute page:

https://dietpi.com/contribute.html

copyrights footer bottom of pages can be updated to 2024, but this page in particular talks about what was done in 2022 and implores the reader to "Enable us to grow in 2023."

Have not cataloged all pages, but there could certainly be other instances of this.

[MichaIng]

We probably just remove that section and shorten the page, to move the actual ways of contributing to the project more up into view, especially on mobile phones.

Updated copyright year: 6f0da6d