Add licence and contributing files

Author: bennuttall

CONTRIBUTING.md

@@ -0,0 +1,29 @@
+# Contributing
+
+All contributions are assumed to be licensed under the same licence as the source, i.e. [CC BY-SA](http://creativecommons.org/licenses/by-sa/4.0/). This licence must remain in all derivatives of this work.
+
+## Issues
+
+If you find a mistake, bug or other problem, please [open an issue](https://github.com/raspberrypilearning/networking-lessons/issues) in this repository.
+
+## Pull Requests
+
+If you fix a mistake, bug or problem or have something to contribute, please create a pull request for each modification. Please consider grouping modifications sensibly, i.e. don't bundle typo fixes in the same pull request as code changes, instead file them separately.
+
+Please note that sometimes things are done for pedagogical reasons so changes which make sense from a software engineering perspective (reducing duplication or making use of more advanced programming language features) may not be suitable to maintain the intended educational value.
+
+## Derivatives
+
+The licence must remain in all derivatives of this work.
+
+## Licence
+
+Unless otherwise specified, everything in this repository is covered by the following licence:
+
+[![Creative Commons Attribution 4.0 International Licence](http://i.creativecommons.org/l/by-sa/4.0/88x31.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+
+***Networking Lessons*** by the [Raspberry Pi Foundation](http://www.raspberrypi.org) is licensed under a [Creative Commons Attribution 4.0 International Licence](http://creativecommons.org/licenses/by-sa/4.0/).
+
+Based on a work at https://github.com/raspberrypilearning/networking-lessons
+
+Lessons 1 and 2 based on ideas and code by [David Whale](https://twitter.com/whaleygeek)

LICENCE.md

@@ -0,0 +1,11 @@
+# Licence
+
+Unless otherwise specified, everything in this repository is covered by the following licence:
+
+[![Creative Commons Attribution 4.0 International Licence](http://i.creativecommons.org/l/by-sa/4.0/88x31.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+
+***Networking Lessons*** by the [Raspberry Pi Foundation](http://www.raspberrypi.org) is licensed under a [Creative Commons Attribution 4.0 International Licence](http://creativecommons.org/licenses/by-sa/4.0/).
+
+Based on a work at https://github.com/raspberrypilearning/networking-lessons
+
+Lessons 1 and 2 based on ideas and code by [David Whale](https://twitter.com/whaleygeek)

README.md

@@ -60,9 +60,10 @@ See the [teacher setup instructions](teacher-instructions.md) for more informati
 
 Unless otherwise specified, everything in this repository is covered by the following licence:
 
-![Creative Commons License](http://i.creativecommons.org/l/by-sa/4.0/88x31.png)
+[![Creative Commons Attribution 4.0 International Licence](http://i.creativecommons.org/l/by-sa/4.0/88x31.png)](http://creativecommons.org/licenses/by-sa/4.0/)
 
-***Networking Lessons*** by the [Raspberry Pi Foundation](http://raspberrypi.org) is licenced under a [Creative Commons Attribution 4.0 International License](http://creativecommons.org/licenses/by-sa/4.0/).
+***Networking Lessons*** by the [Raspberry Pi Foundation](http://www.raspberrypi.org) is licensed under a [Creative Commons Attribution 4.0 International Licence](http://creativecommons.org/licenses/by-sa/4.0/).
 
 Based on a work at https://github.com/raspberrypilearning/networking-lessons
-Lessons 1 and 2 based on ideas and code by @whaleygeek
+
+Lessons 1 and 2 based on ideas and code by [David Whale](https://twitter.com/whaleygeek)