Updates to scheduler constraints and start of docs:

- Adds constraint 10 to scheduler, enforcing tasks cannot be assigned to periods where they don't have enough time to be completed
- Adds ideas for constraints 2 and 9, but further work is needed
- Adds a scheduluerREADME with theory information. This can be generated automatically from the docstrings in constraint explainations.
- Adds a more complex example case to the main block of file for testing

Author: RyanDavies19