add notes around the use of skycons
add notes around the use of skycons

Resolves #121

skyglobal/web-toolkit,image-tester/web-toolkit,aldreth/web-toolkit,aldreth/web-toolkit,image-tester/web-toolkit,image-tester/web-toolkit,skyglobal/web-toolkit,aldreth/web-toolkit,skyglobal/web-toolkit