Update mission statement and related sections

[HeyItsFelipe]

-Replace current mission statement in Our Mission with Building Communities around Technology -Replace About Us section with Our Mission section, but keep About Us text safe as we might need it for later -Remove the two sections below it, but keep Our Goal text safe as we might need it for later It should look like this:

But style it better, like make it centered and stuff. Also update nav as sections will be moved.

[VelazquezLuis]

PR has been merged will close issue