add new methods to the notebooks and readme

Problem

add new methods to the notebooks and readme

What types of changes does your code introduce to causaltune? Put an x in the boxes that apply

[ ] Bugfix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] Documentation Update (if none of the other choices apply)

[x] I have read the CONTRIBUTING doc
[x] Description above provides context of the change
[x] I have added tests that prove my fix is effective or that my feature works
[x] Unit tests for changes (not needed for documentation changes)
[x] Bumping version in setup.py is an individual PR and not mixed with feature or bugfix PRs
[x] Commits follow "How to write a good git commit message"
[x] Relevant documentation is updated including usage instructions