Renamed resizestop event name on API docs

[fedesnieg]

The event name was wrong on the API docs. The correct event name is resizestop

[coveralls]

Coverage remained the same at 65.23% when pulling 9b68d8e on fedesnieg:develop into 590bc34 on gridstack:develop.

[adumesny]

No it is not named wrong (maybe 'resizedone' would been clearer?) - see #398
gs has to have a custom event that is guaranteed to be AFTER the normal resizestop event sent in which we update our sizes, otherwise you might get called first. I'll update the doc.

[radiolips]

Thanks for pointing this out, @fedesnieg , and thanks @adumesny for taking care of updating the docs.