Update README.md

Added sweep-line animation

Author: chubbc

README.md

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 A Julia package for the contraction of tensor networks using the sweep-line-based contraction algorithm laid out in the paper [General tensor network decoding of 2D Pauli codes](https://arxiv.org/abs/2101.04125). This algorithm is primarily designed for two-dimensional tensor networks but contains graph manipulation tools that allow it to function for generic tensor networks.
 
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 Below I have provided some examples of `SweepContractor.jl` at work. Scripts with working versions of each of these examples are also included in the package. For more detailed documentation consult help pages by using `?` in the Julia REPL.
 
 Feel free to contact me with any comments, questions, or suggestions at [[email protected]](mailto:[email protected]). If you use `SweepContractor.jl` for research, please cite either [arXiv:2101.04125](https://arxiv.org/abs/2101.04125) and/or [doi:10.5281/zenodo.5566841](http://dx.doi.org/10.5281/zenodo.5566841).