Readme: Added more (redundant) info n libraries to be installed;

Added output on non configured converters in /index.html statistic
Target: Avoid pitfalls and open questions for beginners

tools/esp8266/README.md

@@ -12,6 +12,10 @@ This code can be compiled using Arduino. The settings were:
 
 - Board: Generic ESP8266 Module
 - Flash-Size: 1MB (FS: none, OTA: 502kB)
+- Install libraries (not included in the Arduino IDE 1.8.19):
+  - Time            Arduino Time library (TimeLib.h)
+  - RF24            Optimized high speed nRF24L01+ driver class documentation
+  - PubSubClient    A client library for MQTT messaging. By Nick O'Leary
 
 ### Optional Configuration before compilation
 

tools/esp8266/app.cpp

@@ -636,6 +636,9 @@ void app::showStatistics(void) {
                     content += F("-> last successful transmission: ") + getDateTimeStr(iv->getLastTs()) + "\n";
             }
         }
+        else {
+            content += F("Inverter ") + String(i) + F(" not (correctly) configured\n");
+        }
     }
 
     if(!mSys->Radio.isChipConnected())