Add R-CMD-check badge to README

Added badges for R-CMD-check to README.

Author: asgr

README.md

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 # ProFuse
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 **ProFound** + **ProFit** + **ProSpect** = **ProFuse**
 
 This is the spectral spatial decomposition package **ProFuse** as discussed in Robotham+ 2022. This work was carried out in close collaboration with Sabine Bellstedt.