Document Transformations (#73)

* Enhance docs in transformations

* Add example figure for transformations

* Apply @mofeing suggestions from code review

Co-authored-by: Sergio Sánchez Ramírez <15837247+mofeing@users.noreply.github.com>

* Rephrase SplitSimplification docs

* Apply suggestions from code review

Co-authored-by: Sergio Sánchez Ramírez <15837247+mofeing@users.noreply.github.com>

* Remove unnecessary docs

* Remove unwanted figure

* Update docs

* Fix tensor network tag

* Change verb in docs

* Fix docstrings

* Apply @mofeing suggestions from code review

Co-authored-by: Sergio Sánchez Ramírez <15837247+mofeing@users.noreply.github.com>

* Fix transformation docs

* Add import

* Delete `transformation.svg` file

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Co-authored-by: Sergio Sánchez Ramírez <15837247+mofeing@users.noreply.github.com>