new home screen, tutorial fxml file and missing javadoc

src/main/java/ch/zhaw/gartenverwaltung/SelectSowDayController.java

@@ -21,6 +21,11 @@ public class SelectSowDayController {
     @FXML
     public ToggleGroup phase_group;
 
+    /**
+     * if sow date radio button was selected return sow date
+     * if sow date was not selected get sow from harvest day and return sow date
+     * @return {@link LocalDate} of the sow date
+     */
     public LocalDate retrieveResult() {
         LocalDate sowDate = datepicker.getValue();
         if (harvest_radio.isSelected()) {
@@ -53,6 +58,10 @@ public class SelectSowDayController {
         harvest_radio.setUserData(GrowthPhaseType.HARVEST);
     }
 
+    /**
+     * Disable save button when date picker is empty
+     * @param saveButton {@link Button} to be disabled
+     */
     public void initSaveButton(Button saveButton) {
         saveButton.disableProperty().bind(datepicker.valueProperty().isNull());
     }