Update README.md

Bedrock2 no longer builds with 8.10

README.md

@@ -23,7 +23,7 @@ Building
 This repository requires [Coq](https://coq.inria.fr/) [8.9](https://github.com/coq/coq/releases/tag/V8.9.0) or later.
 Note that if you install Coq from Ubuntu aptitude packages, you need `libcoq-ocaml-dev` in addition to `coq`.
 Note that in some cases (such as installing Coq via homebrew on Mac), you may also need to install `ocaml-findlib` (for `ocamlfind`) and `ocaml-num`.
-If you want to build the bedrock2 code, you need [Coq 8.10](https://github.com/coq/coq/releases/tag/V8.10.0) or later (otherwise you can pass `SKIP_BEDROCK2=1` to `make`).
+If you want to build the bedrock2 code, you need [Coq 8.13](https://github.com/coq/coq/releases/tag/V8.13.0) or later (otherwise you can pass `SKIP_BEDROCK2=1` to `make`).
 We suggest downloading [the latest version of Coq](https://github.com/coq/coq/wiki#coq-installation).
 
 Alternatively, choose your package-manager to install dependencies: