docs: docs written for new method

src/main/java/edu/ntnu/idatt2001/Wargames/battlesimulation/battle/ArmyFiles.java

 package edu.ntnu.idatt2001.Wargames.battlesimulation.battle;
 
 import edu.ntnu.idatt2001.Wargames.battlesimulation.controllers.SimulationSingleton;
-import edu.ntnu.idatt2001.Wargames.battlesimulation.maintnance.PopupBoxes;
 import edu.ntnu.idatt2001.Wargames.battlesimulation.specificunits.Unit;
 import javafx.stage.FileChooser;
-
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
@@ -13,7 +11,6 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -120,6 +117,7 @@ public class ArmyFiles {
 
     /**
      * method used for checking for illegal characters which can corrupt a file
+     *
      * @param lines a line from the file
      * @return true if the line doesn't consist of illegal characters
      * @throws IllegalArgumentException if an illegal character is found
@@ -142,9 +140,8 @@ public class ArmyFiles {
      * checks if string consist of numbers
      *
      * @param lines string to be checked
-     * @return true or false depending on outcome
      */
-    public boolean checkInputForIntegers(String lines) {
+    public void checkInputForIntegers(String lines) {
         String chekIfInt = "[0-9]+";
         Pattern pt = Pattern.compile(chekIfInt);
         Matcher mt = pt.matcher(lines);
@@ -152,6 +149,5 @@ public class ArmyFiles {
         if (!mt.matches()) {
             throw new IllegalArgumentException("Health value in file is a String, not a Integer");
         }
-        return true;
     }
 }