footer links update

footer links

disable Call for Proposals  
disable Important dates  

FAQ - update with https://wiki.debian.org/DebConf/26/Faq

~~ Become a Sponsor! - update with these amounts , currents and then enable sponsor section in the headers ~~

~~ The amounts for DC26 are (in USD dollar): \level{\textit{Supporter}}{up to $3,000}

 \\level{Bronze}{$3,000} 

\\level{Silver}{$7,500}

\\level{Gold}{$15,000} 

\\level{Platinum}{30,000} ~~

Artwork - update with https://salsa.debian.org/debconf-team/public/data/dc26/-/tree/main