Fixed small error

exercises/run-length-encoding/src/example/java/RunLengthEncoding.java

             toAddTo.append(countOfChar);
         }
 
-        countOfChar.append(toAdd);
+        toAddTo.append(toAdd);
     }
 
     public String decode(String encodedData) {
 
         return decodedData.toString();
     }
-}
+}