Improved Expo Docs organization

As we added more and more docs, they started to feel harder to navigate and less helpful. On our docs home page, we had over 100 docs listed in the sidebar with topics ranging from getting started to advanced niche guides to technical specifications. So, we took a step back and decided to clean up our docs to make them a better place to find information.

Now our docs feature a new organizational structure. Our docs "Home" page features the primary main quest docs that we think every developer will benefit from. Next, we have "Guides", which are our side quests. Some of these guides may help you take your project to the next level. After that, there's a “Reference” section for learning about specific APIs, keys, and values for our SDK and libraries. Finally, there's a new “Learn” section with a brand new tutorial that can guide you through making a universal image editing app.

Learn something new with our docs!