added example for https://plot.ly/~etpinard/270

There are no examples of Bar Charts with hover text.

I took https://plot.ly/~etpinard/270

Maybe this particular plot is an overkill for the api-docs page.
Nobody would actually hard code the JSON object to generate this figure.
We should discuss if or how to include *complicated* examples like this one.

If preferred. I can make a less-complicated example of a Bar Chart with hover text.
I was just having fun with docs 4.0.

@theengineear @chriddyp @alexander-daniel thoughts?