Merge pull request #69 from ascott1/gh-pages

Clean up section nav
Add TOC and introductory section
Format sections
Format sections
Format sections
Update TOC
Format sections
Format intro section
Format intro and sections, add placeholders for images
Format sections
Add "Asset library" section
Format intro and sections
Format sections
Format intro and sections
Format sections
Add section header
Removed "principles" from page title
Correct hex for red orange 20%
Merge pull request #74 from theresaanna/gh-pages

Correct hex for red orange 20%
Remove numbering from "Examples of misuse"