Add literature references as further reading

[magnuspalmblad]

SCOPE has now been used in a number of publications, e.g.

Palmblad et al. (https://doi.org/10.1016/j.trac.2023.116946)
Bergman et al. (https://doi.org/10.1021/jasms.4c00293)

Furthermore, the Gaussian smoothing preprint (https://doi.org/10.48550/arXiv.2005.09941) describing how this is achieved in SCOPE has been cited by Li et al. (https://doi.org/10.1080/17538947.2024.2392835).

I would suggest adding all four of these as further reading.