GitKraken login

[jihe-liu]

Note in the tutorial: when 'Authorize Axosoft' using github account, it might not work properly if the browser is IE. Switch to Chrome/Firefox and try again.

[rkhetani]

When connecting GitHub to GitKraken, make sure that the authorization is performed on either Chrome or Firefox and not on Internet explorer.

Add note to 02_Gitkraken.md