Potential additions to float module docs

[mooreryan]

I think it may be helpful to include similar language in the float module as is present in the tour regarding infinities and nan.

The tour has this:

Under the JavaScript runtime, exceeding the maximum (or minimum) representable value for a floating point value will result in Infinity (or -Infinity). Should you try to divide two infinities you will get NaN as a result.

Something like that would probably be good to have in the float module as well. I'm not sure if there should be suggestions on how to handle these values, since the float module doesn't provide functions for dealing with them.

[lpil]

Perhaps we could have the same text as in the tour?