fixed replyPakcet to replyPacket (#4439)

Fixed variable name

Author: arush15june

doc/esp8266wifi/udp-examples.rst

@@ -106,7 +106,7 @@ The sketch performing all described functionality is presented below:
     WiFiUDP Udp;
     unsigned int localUdpPort = 4210;  // local port to listen on
     char incomingPacket[255];  // buffer for incoming packets
-    char  replyPacekt[] = "Hi there! Got the message :-)";  // a reply string to send back
+    char  replyPacket[] = "Hi there! Got the message :-)";  // a reply string to send back
 
 
     void setup()
@@ -144,7 +144,7 @@ The sketch performing all described functionality is presented below:
 
         // send back a reply, to the IP address and port we got the packet from
         Udp.beginPacket(Udp.remoteIP(), Udp.remotePort());
-        Udp.write(replyPacekt);
+        Udp.write(replyPacket);
         Udp.endPacket();
       }
     }