Performance guide

[ivanmalagon]

As CARTO.js v4 adoption gets bigger, we see that the relation among source, layer, style and dataview is not clear.
Several apps we've seen don't know about the reactivity to a layer or dataview when changing the query in the source. They end up killing the existing instances and creating new ones where a simple call to setQuery would make the trick.

Let's create a guide after Quickstart explaining in detail and with graphics these concepts. We can call it performance tips so people pay more attention to it.

[jesusbotella]

Here's the first approach to the performance guide:
http://filters-docs.developers.carto-staging.com/developers/carto-js/guides/performance-tips/