Histograms nbinsx and nbinsy descriptions are wrong

[yankev]

Example:
After setting the nbinsx parameter to 20, the number of bins showing is 15. Also tried with other values for nbinsx, and results vary.

https://jsfiddle.net/2k0q2yg8/

[etpinard]

Ha. That's a description bug.

nbinx doesn't directly set the number of bins but the maximum number of bins allowed by the autobin algorithm. The autobin algorithm attempts to keep the bin size nice.

The old plot.ly workspace got this right:

i.e. that Max # X bin row.

For fully custom bin sizes, you should use xbins.start, xbins.end, xbins.size.

Changing the issue accordingly.

[etpinard]

@yankev wanna try to make PR for this?