Add citation to "About" section of repo

[motiwari]

Similar to https://github.com/tdunning/t-digest

[Allan0820]

@motiwari I think it would be best if you and the team fill this out to generate a citation in the citation file format.

https://citation-file-format.github.io/cff-initializer-javascript/#/

[Allan0820]

@motiwari have you tried the link, I think only the authors could fill that.