A mismatch of the strip option in the validate API

[makinoshi]

Hi, funcool. Thank you for your creating nice validation library.

I've found a mismatch between document and its work.

validate API's comment says,

This function by default strips all data that are not defined in schema, but this behavior can be changed by passing {:strip false} as third argument.

but actually default value of strip is false. https://github.com/funcool/struct/blob/master/src/struct/core.cljc#L129

Which have you intended?