Improve documentation navigation

[donaldpipowitch]

Before undergoing a substantial to docs or the codebase, please open up an issue to make sure it's a desired change.

I'd like to improve the navigation in these ways:

• If the user clicks on Read the docs on the homepage, he/she will be redirect to https://blocks-ui.com/docs. I'd like to redirect to https://blocks-ui.com/getting-started/ as the starting point for the documentation.
• Highlight the currently active page in the side navigation.
• Add proper WIP description to the pages missing content.
• Add prev/next navigation to the pages at the bottom. (Helps to get to the next docs page - especially on mobile.)

Would that be okay?

[johno]

That would be great @donaldpipowitch!