Wording improvement

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 009ed06..75df65b 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -2179,7 +2179,7 @@
  * in mbedtls_config.h.
  *
  * If the symbol #MBEDTLS_PSA_CRYPTO_CONFIG_FILE is defined, it specifies
- * an alternative location to use instead of include/psa/crypto_config.h.
+ * an alternative header to include instead of include/psa/crypto_config.h.
  *
  * If you enable this option and write your own configuration file, you must
  * include mbedtls/config_psa.h in your configuration file. The default