GH3508 added basic documentation of google analytics
closes #3508 

Thanks! This was so much needed.

I would add the `filters` parameter as well on the code block.
 @manugarri filters added.
 Would it be better suited to put this in remote_data.rst instead of io.rst?
 hmm, I thought I mentioned that previously.....

@benoitpointet this should go in `remote_data.rst`
 Yep indeed, that's what you said. However GBQ is in `io.rst`. What's the rule there? 
 gbq allows full IO

ga is just a remote data pull

so remote_data is more appropriate
 closing in favor of #8835. FYI for the future, you can simply `push -f` to overwrite these commits rather than opening another pr, but ok for this one.
