Update Formatting and Style guidelines

This MR:

• Makes the language more accurate
• Uses lists more often (best practice)
• Mentions the snippet shortcode
• Provides more examples (taking advantage of the fact the guidelines are in Hugo)
• Adds more tree
• Adds syntax highlighting for code blocks where needed
• Clarifies style
• Adds more references for people to read/watch

I'll be merging if there are no objections.