Add notes on X2 data to docs folder
Add notes on X2 data to docs folder

+ Fixes #510

erose/studentinsights,erose/studentinsights,jhilde/studentinsights,erose/studentinsights,studentinsights/studentinsights,studentinsights/studentinsights,erose/studentinsights,jhilde/studentinsights,jhilde/studentinsights,studentinsights/studentinsights,studentinsights/studentinsights,jhilde/studentinsights