Template: Update Style Guide with Materialize CSS

[mike-diff]

Update the style guide with Materialize CSS.
templates/views/style-guide.hbs

• Pick out an awesome color theme (http://colormind.io/ is a good one to use)
• Headings
• P Tags
• Anchor links
• Add button styles
• Any other helpful elements.
  Get your inner designer on and pick the color theme for this project. Create a nice looks and feel that we'll all use for the page elements and UX.
  https://materializecss.com/