not sure if this is the right place for this
it's easy to miss that there are more color functions that the seven on this page:
I didn't realize it until today. This section of documentation to be extended to include more examples or at least link to relevant less.js documentation: http://lesscss.org/functions/#color-operations
We're missing a function or two that we should add. I don't want to link to LESS docs since confusing carto & less has been a common point of user confusion & frustration.
Also needs to be fixed in the primary documentation: https://www.mapbox.com/carto/api/2.1.0/#color
update color function docs, closes #137