Move contributor guide to separate file

CONTRIBUTING.md

@@ -0,0 +1,9 @@
+# How to collaborate
+
+You can [open an issue](https://help.github.com/articles/creating-an-issue/) and give us your suggestions as to how we can improve this guide, or what we can do to improve the learning experience.
+
+You can also [fork this project](https://help.github.com/articles/fork-a-repo/) and send a [pull request](https://help.github.com/articles/using-pull-requests/) to fix any mistakes that you have found.
+
+If you want to suggest a new resource, send a pull request adding such resource to the [extras](https://github.com/open-source-society/computer-science/tree/master/extras) section.
+
+The **extras** section is a place where all of us will be able to submit interesting additional articles, books, courses and specializations, keeping our curriculum *as immutable and concise as possible*.

README.md

@@ -538,18 +538,6 @@ Now we have a stable version of the curriculum, which won't change anymore, only
 
 Our students can trust in this curriculum because it has been carefully planned and covers the major core topics that a conventional Computer Science program covers.
 
-# How to collaborate
-
-You can [open an issue](https://help.github.com/articles/creating-an-issue/) and give us your suggestions as to how we can improve this guide, or what we can do to improve the learning experience.
-
-You can also [fork this project](https://help.github.com/articles/fork-a-repo/) and send a [pull request](https://help.github.com/articles/using-pull-requests/) to fix any mistakes that you have found.
-
-If you want to suggest a new resource, send a pull request adding such resource to the [extras](https://github.com/open-source-society/computer-science/tree/master/extras) section.
-
-The **extras** section is a place where all of us will be able to submit interesting additional articles, books, courses and specializations, keeping our curriculum *as immutable and concise as possible*.
-
-**Let's do it together! :smile:**
-
 # Community
 
 Subscribe to [/r/opensourcesociety](https://www.reddit.com/r/opensourcesociety/)!
@@ -580,4 +568,4 @@ Add **Open Source Society University** to your [Facebook](https://www.facebook.c
 - [Stanford University](https://lagunita.stanford.edu/)
 - [MIT Open Courseware](http://ocw.mit.edu/courses/#electrical-engineering-and-computer-science)
 - [A DIY Computer Science Education](https://bradfieldcs.com/diy/)
-- [Obtaining a Thorough CS Background Online](http://spin.atomicobject.com/2015/05/15/obtaining-thorough-cs-background-online/)
+- [Obtaining a Thorough CS Background Online](http://spin.atomicobject.com/2015/05/15/obtaining-thorough-cs-background-online/)