Implement documentation for components as a Launcher/Nerdlet

[tangollama]

• Listing of components on the left
• Rendered code
• Code snippet + documentation

[danielgolden]

Here's a prototype of the design for the docs (be sure to scroll).

[devfreddy]

To Do's

• [x] Make side-navigation into component and hide
• [x] Remove readme, but add link to it

Post-poning

• [ ] Now that we've detached the readme contents, setup ReactVisibilitySensor to work with sidenav

[danielgolden]

Added link for readme: 1b1cd827eac10ea6bf2692daf198e950aa2d0a94