Move MBEDTLS_ERROR_C to section "General configuration options"

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/docs/proposed/config-split.md b/docs/proposed/config-split.md
index 40ebb50..69a45b8 100644
--- a/docs/proposed/config-split.md
+++ b/docs/proposed/config-split.md
@@ -369,6 +369,7 @@
 
 #### SECTION General configuration options
 ```
+#define MBEDTLS_ERROR_C
 //#define MBEDTLS_CONFIG_FILE "mbedtls/mbedtls_config.h"
 //#define MBEDTLS_USER_CONFIG_FILE "/dev/null"
 ```
@@ -377,7 +378,6 @@
 #### SECTION TLS feature selection
 ```
 #define MBEDTLS_DEBUG_C
-#define MBEDTLS_ERROR_C
 #define MBEDTLS_SSL_CACHE_C
 #define MBEDTLS_SSL_CLI_C
 #define MBEDTLS_SSL_COOKIE_C