Make it easier to navigate guides

[paulcsmith]

• Put all guides in the left card. Easier to see where you are, navigate to other sections, and remember what you've already seen
• Put table of contents for the guide at the top. It flows nicely and makes it easy to see what the guide will talk about
• Add the "Next guide" button to the bottom and style it.

[paulcsmith]

Thanks for taking a look @edwardloveall!

[paulcsmith]

And thanks to @rishavs for the ideas