Implement hub button on main site footer and subsite footers

[cjyabraham]

@thetwopct Could you implement the new "All CNCF Sites" button on the CNCF main site and one subsite, say, the Glossary? I can then propagate it to the other subsites. The design is in figma. The hub page it should link to is here.

Reminder for myself: implement that language dropdown consistently across all subsite mobile footers.

• [x] www.cncf.io
• [x] glossary PR
• [x] contribute PR
• [x] maturitymodel PR
• [x] app-delivery PR
• [x] sustainability PR
• [x] runtime PR
• [x] security PR
• [x] jobs
• [x] community request
• [x] store

[cjyabraham]

Main site button is deployed.

[thetwopct]

I've added to Contributors and Glossary, this should give you enough to copy to any other sites using similar templates

[thetwopct]

Store now has the hub button, and with that, let's close! 👍 🎉