Mission of .opam files in this repo

[QinshiWang]

I'm not sure about the mission of .opam files in this repo. I suppose they serve as OPAM files for the dev version, and prepare for the next release. But the dev version OPAM files are actually stored at https://github.com/coq/opam-coq-archive/tree/master/extra-dev/packages/coq-vst. The OPAM files in this repo are quite different from the released versions.

These .opam files don't work, either. It is because [make "ZLIST=platform" "BITSIZE=64" "-j%{jobs}%" "vst"] will only build proofauto but not examples, but [make "ZLIST=platform" "BITSIZE=64" "install"] will try to install some examples.