Add some docs to show how to create custom template tags. Closes #1206
Add some docs to show how to create custom template tags. Closes #1206

dokterbob/satchmo,ringemup/satchmo,Ryati/satchmo,Ryati/satchmo,twidi/satchmo,dokterbob/satchmo,twidi/satchmo,ringemup/satchmo