Adding calls to action on the fab.city homepage and moving some sections.

[Katearmstrong4]

Hi @tuengominh!
Using this as the style guide:
https://space10.io/

I would like to make two new sections on the fab.city page.
Instead of these sections:

1. Under 'Our Approach" I'd like to add a section of three:
   Prototype the city
   We engage in action-research directly in the city by prototyping and deploying strategies across localities in our network. Read about the prototyping method.
   Common knowledge
   As a global network, we are connected through the knowledge we share, across common tools and platforms. See the handbook
   Documentation
   Findings from prototyping and action-research are documented and shared within the network.
   Read the blog or join our social media channels add buttons for Facebook, Twitter

Then another section of three above the new events section you made:
I can add the content here later :-)

Let me know if this is clear!

[tuengominh]

I sent the link in the pull request Add collaborators & Event section #10 :)