These files are modified variants of the ones included in Coq's standard
distribution. The original materials feature the GPL 2.1 license in each
file's header, which was suspiciously removed from Linguist's samples.
https://github.com/coq/coq/tree/trunk/theories
Basics.v is a different file to that found in Coq's distro, but is vague
in origin and being removed to err on the side of caution. The remaining
samples are from a MIT-licensed online course by Software Foundations:
https://www.cis.upenn.edu/~bcpierce/sf/current/
References: github/linguist#3313