Document check-config.h and *adjust*.h as internal headers

Including *adjust*.h directly is likely to cause them to be applied at the
wrong time, resulting in an invalid or unintended configuration.

Including check_config.h at the wrong time is likely to cause spurious
errors.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/psa/crypto_adjust_auto_enabled.h b/include/psa/crypto_adjust_auto_enabled.h
index 63fb29e..e2618d1 100644
--- a/include/psa/crypto_adjust_auto_enabled.h
+++ b/include/psa/crypto_adjust_auto_enabled.h
@@ -2,6 +2,8 @@
  * \file psa/crypto_adjust_auto_enabled.h
  * \brief Adjust PSA configuration: enable always-on features
  *
+ * This is an internal header. Do not include it directly.
+ *
  * Always enable certain features which require a negligible amount of code
  * to implement, to avoid some edge cases in the configuration combinatorics.
  */