added license, expanded readme

LICENSE

@@ -0,0 +1,8 @@
+The MIT License (MIT)
+Copyright (c) 2018 Contextual Dynamics Laboratory (www.context-lab.com)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -5,3 +5,16 @@ This repository contains materials for a short MATLAB and computational neurosci
 You'll probably want to start by downloding [this PDF](https://github.com/ContextLab/computational-neuroscience/blob/master/main.pdf), which contains the syllabus, course notes, and problem sets.
 
 Lecture slides, code, and other materials mat be found by exploring the rest of the repository.
+
+# Using this material
+
+Want to use this material in your course?  Feel free!  You are welcome to use, modify, redistribute, etc. all of the materials for this course.  However, (while we have done our best to produce high quality, accurate, materials) we can make no guarantees that the information or code provided is correct.  If you notice an error or have a question, [post an issue](https://github.com/ContextLab/computational-neuroscience/issues) about it!
+
+# Contributing
+
+To add new material to the course, or to modify the existing content, please follow these steps:
+1. Fork this repository
+2. Make your modifications on your fork
+3. Submit a pull request with an informative message describing what you changed
+
+Or, to add an idea or propose a change for someone else to make, create a new [issue](https://github.com/ContextLab/computational-neuroscience/issues) describing what you're thinking.