State explicitly that any API depending on PSA is unstable
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 2341ef5..1f37d08 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -1626,6 +1626,10 @@
  * not covered yet, but parts that are not ported to PSA yet will still work
  * as usual, so enabling this option should not break backwards compatibility.
  *
+ * \warning  Support for PSA is still an experimental feature.
+ *           Any public API that depends on this option may change
+ *           at any time until this warning is removed.
+ *
  * Requires: MBEDTLS_PSA_CRYPTO_C.
  */
 //#define MBEDTLS_USE_PSA_CRYPTO