Merge pull request #41 from AeneasVerif/son-readme

Add a mention to the Zulip in the README

README.md

@@ -17,6 +17,8 @@ internal language to a pure lamdba calculus.  It is intended to be used in combi
 representation called LLBC. It currently has backends for [F\*](https://www.fstar-lang.org),
 [Coq](https://coq.inria.fr/), [HOL4](https://hol-theorem-prover.org/) and [LEAN](https://leanprover.github.io/).
 
+If you want to contribute or ask questions, we strongly encourage you to join the [Zulip](https://aeneas-verif.zulipchat.com/).
+
 ## Project Structure
 
 - `src`: the OCaml sources. Note that we rely on [Dune](https://github.com/ocaml/dune)