added license

LICENSE.md

+## Instructional Material
+
+The instructional material in this repository is licensed under a [Creative
+Commons Attribution-ShareAlike 4.0 International
+License](http://creativecommons.org/licenses/by-sa/4.0/).
+
+The following is a human-readable summary of (and not a substitute for) the
+[license](https://creativecommons.org/licenses/by-sa/4.0/legalcode).
+
+#### You are free to:
+
+- **Share** - copy and redistribute the material in any medium or format
+
+- **Adapt** - remix, transform, and build upon the material for any purpose,
+even commercially
+
+> The licensor cannot revoke these freedoms as long as you follow you follow
+the license terms. 
+
+#### Under the following terms:
+
+- **Attribution** - You must give appropriate credit, provide a [link to the
+license](https://creativecommons.org/licenses/by-sa/4.0/), and indicate if
+changes were made. You may do so in any reasonable manner, but not in any way
+that suggests the licensor endorses you or your use.
+
+- **ShareAlike** - If you remix, transform, or build upon the material, you
+must distribute your contributions under the same license as the original.
+
+- **No additional restrictions** - You may not apply legal terms or
+technological measures that legally restrict others from doing anything the
+license permits.
+
+#### Notices:
+
+- You do not have to comply with the license for elements of the material in
+the public domain or where your use is permitted by an applicable exception or
+limitation.
+
+- No warranties are given. The license may not give you all of the permissions
+necessary for your intended use. For example, other rights such as publicity,
+privacy, or moral rights may limit how you use the material.
+
+## Software
+
+The example programs and software in this repository are licensed under the
+[MIT license](http://opensource.org/licenses/mit-license.html).
+
+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.