Design: add features section to the welcome page

[lakesare]

https://www.memcode.com/articles/welcome is our landing page.

There needs to be a section with our features. Example of the features are:

• one of the only sites with the gifs allowed!
• accessible, navigate by shortcuts and tabs
• beautiful
• fast course creation
• formatting for free, for all, - formulas, code highlighting
• good for studying at nighttime (look at our colors!)
• SM2 algorithm
• open source

This section should be interesting to read, - consider adding some icons.