Docs about CIBW_PYODIDE_VERSION

docs/setup.md

@@ -113,7 +113,14 @@ Pre-requisite: you need to have a matching host version of Python (unlike all
 other cibuildwheel platforms). Linux host highly recommended; macOS hosts may
 work (e.g. invoking `pytest` directly in [`CIBW_TEST_COMMAND`](options.md#test-command) is [currently failing](https://github.com/pyodide/pyodide/issues/4802)) and Windows hosts will not work.
 
-You must target pyodide with `--platform pyodide` (or use `--only` on the identifier).
+You must target Pyodide with `--platform pyodide` (or use `--only` on the identifier).
+
+!!!tip
+
+    It is also possible to target a specific Pyodide version by setting the `CIBW_PYODIDE_VERSION` environment variable to the desired version. Users are responsible for setting an appropriate Pyodide version according to the `pyodide-build` version. A list is available in Pyodide's [cross-build environments metadata file](https://github.com/pyodide/pyodide/blob/main/pyodide-cross-build-environments.json) or can be
+    referenced using the `pyodide xbuildenv search` command.
+
+    This option is **not available** in the `pyproject.toml` config.
 
 ## Configure a CI service