Add flow control to platform rnd buf

Signed-off-by: Shelly Liberman <shelly.liberman@arm.com>
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 43a9830..ee25107 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -2988,7 +2988,7 @@
  *
  * Uncomment to provide your own alternate implementation for mbedtls_platform_fault(),
  * used in library/platform_util.c to signal a fault injection in either
- * mbedtls_platform_memcpy or mbedtls_platform_memset.
+ * mbedtls_platform_memcpy, mbedtls_platform_memset or mbedtls_platform_random_buf.
  *
  * You will need to provide a header "platform_fault.h" and an implementation at
  * compile time.