Add docs for `chain` about function as second argument
Add docs for `chain` about function as second argument

It was discussed in https://github.com/ramda/ramda/issues/2480#issuecomment-368917060
davidchambers/ramda,davidchambers/ramda,ramda/ramda,CrossEye/ramda,CrossEye/ramda,ramda/ramda,Bradcomp/ramda,ramda/ramda,Bradcomp/ramda,CrossEye/ramda