Further updates to layout

[LukeHandle]

• Add icons for DigitalOcean and GitHub
• Typo on "grow"
• Add Username/UUID examples
• Standardise on no .png extension on images
• Change examples to be just the URL vs. HTML embed example
• pre should overflow/scroll right
• Hide @connor4312's avatar vs. @clone1018's on mobile (if we had a UUID/valid skin, then we could hide somebody else instead :crying_cat_face: )