Could somebody explain how I can add 'Export As' as an action script in Photoshop CC 2015? I just want to automate saving icons to svg.
Not quite sure that you can add that exact option to an action. But here's what you can do instead:
File -> Export -> Export Preferences then change your preferences to something like this (you could make that part of your action too if you'll need to change this frequently):
Quick Export Location is set to
Export files to an assets folder next to the current document
Now, record an action an when you're ready for the export go to
File -> Export -> Quick Export as SVG and it will get added to your action.