`Area`'s `fillOpacity` is not documented in the `Area` page

[Fullchee]

fillOpacity is used in the AreaChart example

https://recharts.org/en-US/api/AreaChart

but it's not in the Area page

https://recharts.org/en-US/api/Area

[ckifer]

hi @Fullchee

fillOpacity is an svg property which recharts passes down to the path element. I'm not sure if it should be a prop that is added to the documentation or not.

@nikolasrieble what do you think of props like this that are SVG props rather than actual recharts props?