Update Release notes (PR#3666)
can you add to original PR pls
 echoing @jreback in a bit more detail: when you want to update a previous PR just make your changes in the original branch (`patch-1`) or in another and `git merge` in the original, squash if you want and then push to the original PR.
 Ok, I made the first batch of edits on my desktop but this most recent was done via github. It creates a new branch for you when you edit a file not in your own repo. I'll have to look into merging and squashing once I get time to write some tests.
 here's a short explanation of both:

`git merge <a-branch-name>` will take the union of the commits of the current branch and the one in `<a-branch-name>`. it's nice for when u create a branch (they are cheap as u probably know) off of another branch for example and then u want to go back to ur original and bring the changes from the branch u just made. it does leave ugly messages about merging and so forth so...

`git rebase` allows you to change the history (squash is a possible action you can take when u do `git rebase -i`) which is not necessarily a good thing if you've pushed to a remote and a bunch of people depend on ur changes. for PRs it's usually ok since they get merged when you are finished. i use it all the time for PRs because i make a bunch of tiny commits for anything significant and i _really_ don't want to lose stuff and then i usually want to get rid of commits that say dumb things like "arg" or "clean up" or any changeset that isn't really interesting

another thing you probably want to do on occasion and right before you declare that your PR is ready to be merged is to say `git fetch upstream && git rebase upstream/master` since that will help people doing the merging by make _you_ deal with merge conflicts :) not that we're lazy but since it's your changeset you'll be able to deal the conflicts most efficiently. `git remote add upstream git://github.com/pydata/pandas.git` will add `upstream` to your list of remotes. other people may have different workflows, but this is what works for me. i can attest to the fact that the people here have been very patient and helpful with my (lack of) knowledge about git especially @y-p so i just wanted to pay it forward so to speak.

(there's tons more to learn and there are about a billion options for every `git` command) just want to give u a sort of "everyday" picture of how i use them, other may use them diffferently
 Hey @cpcloud and @reubano, I thought I'd chime in here. 

@cpcloud, that's a really friendly, yet thorough, explanation for a productive git workflow and one I had to discover by trial and error when I first started using it (thanks to many here, including @wesm). It covers the merge vs. rebase debate fairly, and I feel is the most common workflow used within this community of developers. Is there anyway we could clean this up just a tad and use in the developers page, under the section, [_Working with the code_](http://pandas.pydata.org/developers.html#working-with-the-code)? If so, it could help new contributors overcome the intimidation of initial git exposure and be more proficient with their contributions!

Anyways, just my thoughts. Thanks!
 i agree!

@cpcloud 
dev page is in this repo (which u can push to)
https://github.com/pydata/pandas-website
 Will do. I also had to discover this somewhat by trial and error. Certain things such as scm breeze make git a bit more user friendly. One thing that frustrates me is that I never really get a chance to use git for anything really complex since if you rebase onto upstream all the time usually you only get merge conflicts with release notes or what's new docs. Maybe that's a good thing :) 
 You should definitely add the `git rebase upstream/master` to the dev notes if it isn't already there - that was an incredibly useful shortcut for working with pandas.
 so much so that i have `alias gfrb='git fetch upstream && git rebase upstream/master'` in my `.zshrc`
 i will add this to the dev page...might take a day or so
 @reubano can you mve the relase notes to your original PR? thanks
 I updated the original PR. So how do I remove this one? Haven't had time to make tests though.
 just click close!
 link to #3666
 FYI check the [git workflows wiki page](https://github.com/pydata/pandas/wiki/Git-Workflows)
