Fix example on the site

[abbasovalex]

Hi, there is unpleasant typo into the site's example http://policystat.github.io/jobtastic/
Please, replace from:
significant_kwargs = [
('numerators', str),
('denominator', str),
]
to:
significant_kwargs = [
('numerators', str),
('denominators', str),
]

[josephmisiti]

Just fixed it in a pull request, as I ran into this also.

#27

[winhamwr]

Thank you both, Аббасов and joseph. The typo is now toast.

-Wes