Move MBEDTLS_SELF_TEST option

Move MBEDTLS_SELF_TEST option to
the "General and test configuration options"
section as MBEDTLS_VERSION_C.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/docs/proposed/config-split.md b/docs/proposed/config-split.md
index 17a4e7b..4974bbd 100644
--- a/docs/proposed/config-split.md
+++ b/docs/proposed/config-split.md
@@ -144,6 +144,7 @@
 //#define MBEDTLS_DEPRECATED_WARNING
 //#define MBEDTLS_DEPRECATED_REMOVED
 //#define MBEDTLS_CHECK_RETURN_WARNING
+#define MBEDTLS_SELF_TEST
 //#define MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN
 //#define MBEDTLS_TEST_CONSTANT_FLOW_VALGRIND
 //#define MBEDTLS_TEST_HOOKS
@@ -199,7 +200,6 @@
 //#define MBEDTLS_SHA256_SMALLER
 //#define MBEDTLS_SHA512_SMALLER
 //#define MBEDTLS_RSA_NO_CRT
-#define MBEDTLS_SELF_TEST
 //#define MBEDTLS_BLOCK_CIPHER_NO_DECRYPT
 //#define MBEDTLS_GCM_LARGE_TABLE
 //#define MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_IF_PRESENT