When creating a new "dune repo" for Coq, if we don't mention (using coq 0.2) in dune-project (eg. not creating the file), the first dune build will append (using coq.theory 0.2) to the file, yet the following dune builds expect (using coq 0.2).

First reported by:
I ran into issue 2/3 as well: Info: appending this line to dune-project: (using coq.theory 0.1) is wrong; it needs to append (using coq 0.1) instead. I also mistakenly used filename.v instead of filename at first in the list of module; it would be nice to have examples in the doc.

Originally posted by @cpitclaudel in #2042 (comment)