fix link name

Author: d-a-v

doc/faq/readme.rst

@@ -185,4 +185,4 @@ This was WiFi persistence. Starting from version 3 of this core, WiFi is
 indeed off at boot and is powered on only when starting to be used with the
 regular API.
 
-Read more at `wifiOffAtBoot <../esp8266wifi/generic-class.rst#persistent>`__.
+Read more at `former WiFi persistent mode <../esp8266wifi/generic-class.rst#persistent>`__.