Clarify chaining docs again

[hnordt]

With v1.2.4 you can now write _.chain(list) instead _(list).chain()

The sentence:

"Calling chain on a wrapped object will cause all future method calls to return wrapped objects as well. When you've finished the computation, use value to retrieve the final value."

Should be modified to something like:

"Calling chain will cause all future method calls to return wrapped objects. When you've finished the computation, use value to retrieve the final value."

Because with the first sentence we can misinterpret that we can only use chain in "wrapped mode" (_(list).chain())

[jashkenas]

Good point -- thanks!