Update README.md

Author: horihiro

README.md

@@ -9,7 +9,7 @@ This library depends on Google Translate Service.
   - use Arduino Core for ESP8266 **2.5.0** or later<br>
   or
   - download [ESP8266mDNS.cpp](https://github.com/mblythe86/Arduino/blob/master/libraries/ESP8266mDNS/ESP8266mDNS.cpp)/[.h](https://github.com/mblythe86/Arduino/blob/master/libraries/ESP8266mDNS/ESP8266mDNS.h) to  `$LIBRARIES_DIR/esp8266-google-home-notifier/src/` and restart Arduino IDE. <br>
-    (note: these are merged into the library included in 2.5.0)
+    (note: these files [will be merged](https://github.com/esp8266/Arduino/pull/3107) into 2.5.0)
 - [esp8266-google-tts](https://github.com/horihiro/esp8266-google-tts) <br>
   download from Library Manager of Arduino IDE