MINOR: Updated changelog for v2.1.0
MINOR: Updated changelog for v2.1.0

Internetrix/advancedworkflow,dnadesign/advancedworkflow,silverstripe-terraformers/advancedworkflow,silverstripe-terraformers/advancedworkflow,silverstripe-australia/silverstripe-advancedworkflow,silverstripe-australia/advancedworkflow,silverstripe-australia/advancedworkflow,dnadesign/advancedworkflow,icecaster/advancedworkflow,Internetrix/advancedworkflow,silverstripe-australia/silverstripe-advancedworkflow,icecaster/advancedworkflow