adding contribution guidelines

README.md

@@ -12,6 +12,7 @@ Table of Contents
 - [CS Theory](#cs-theory)
 - [Introduction to CS](#introduction-to-cs)
 - [Misc](#misc)
+- [Contributing](#contributing)
 
 Courses
 ---
@@ -242,5 +243,8 @@ Courses
   - [Experiences](http://philipmjohnson.github.io/ics314f13/experiences/)
   - [Assessments](http://philipmjohnson.github.io/ics314f13/assessments/)
 
+### Contributing
+Have a few courses in mind that you think are awesome and would fit in this list? Feel free to send a [pull request](https://github.com/prakhar1989/awesome-courses/pulls). However, do note that I'm not keen on adding popular courses (such as MOOCs / MIT OCW) as there are sevices like [ClassCentral](https://www.class-central.com/) doing a great job of aggregation. This list is ideally for courses which are relatively unknown and make their material (assignments, lectures, exams etc.) available online for free.
+
 -----
-*Note* For some reason, I'm unable to get emojis to work on this readme (see [issue](https://github.com/prakhar1989/awesome-courses/issues/29) for context). If you are able to get them to work (or identify the issue), I'd appreciate help with adding emojis for courses. Thanks!
+*Note* For some reason, I'm unable to get emojis to work on this readme (see [issue](https://github.com/prakhar1989/awesome-courses/issues/29) for context). If you are able to get them to work (or identify the issue), please let me know. Thanks!