shell → shell-session syntax

These are not shell scripts but rather a shell session

Author: toastal

data/tutorials/platform/1_07_code_formatting.md

@@ -14,14 +14,14 @@ Automatic formatting with OCamlFormat requires an `.ocamlformat` configuration f
 An empty file is accepted, but since different versions of OCamlFormat will vary in formatting, it
 is good practice to specify the version you're using. Running
 
-```shell
+```shell-session
 $ echo "version = `ocamlformat --version`" > .ocamlformat
 ```
 
 creates a configuration file for the currently installed version of OCamlFormat.
 
 In addition to editor plugins that use OCamlFormat for automatic code formatting, Dune also offers a command to run OCamlFormat to automatically format all files from your codebase:
 
-```shell
+```shell-session
 $ opam exec -- dune fmt
-```
+```