All markdown in the same folder
This is a structural refactoring. The only content that changed was to update some links that were broken by file renames.
Having all the markdown files in the top level src directory has some benefits:
- it makes lopsidedness and imbalance in filecount between chapters easier to spot
- the chapter section prefix "chXX-XX" is both sortable and easy to parse, which opens us up for some helpful scripts
Other changes:
- remove commented out sections in SUMMARY.md, mostly in the Design chapter. We'll need to re-assess each as we edit for content.
- move non-markdown static assets to an assets directory
Edited by Coleman McFarland