Revamp website style and contents

Introduce a fresh look for the site for Plasma 6:

• Rework get page with distribution list so that it's easier to read
• Add a new apps page, moving the apps list out of the homepage
• Rework menu layout so important pages aren't buried (ex. community, docs)
• Add jumbotron page headers
• Rework some contents of the homepage
• Change default font to Inter
• Don't link to findyourway page since it is not up-to-date at all

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