Update author list in Plot Spitzer IRS Spectra

[troyraen]

@jkrick will you update this now that https://github.com/IPAC-SW/ipac-sp-notebooks/pull/167 is merged? (will turn this into an issue)

Originally posted by @troyraen in #285 (comment)

Need to update the names and also move the list up into the frontmatter.