vuejs structure for each lesson

[headwinds]

I really like your initiative to create this guide - I thought it might be nice to break up the index page into individual lessons using VueJS so that a contributor can focus on either adding or creating the lesson itself.

I've created this PR as a start so that you could review the structure - I don't intend for it be merged into master just yet but possibly left as a branch until the all the lessons are moved into their own files.

In the end there would be a folder for each main section: Math, Control Flow, String, etc... and list of lessons within each.

Thoughts?