Add gold theme - #430

Changed pages include:

• index.html - view
• about.html - view
• generator.html - view
• learn.html - view
• outlines.html - view
• revise.html - view
• learn/connecting-letters.html - view
• learn/disemvowelment.html - view
• learn/further-resources.html - view
• learn/history.html - view

There are more changes not included in the list