Look and Feel

[oubiwann]

This epic is continuation of the v3.0 epic: #66

Features/tasks:

• Create a docs style guide - Create a docs style guide #53
• Produce v3 of the LFE Docs Site - Produce v3.0 of the LFE Docs Site #62
• Support Syntax Highlighting for Code - Support Syntax Highlighting for Code #91
• Fix up SASS/CSS for Mobile - Fix up SASS/CSS for Mobile #104

Part of release #95

[oubiwann]

We're going to ditch the docs site with all serious content going into LFE books, and general docs content going to lfe.io/docs