修改编辑器 forth 拼错bug

OTSPartA_STDEditor/UI/STDEditor.cs

@@ -55,7 +55,7 @@ namespace OTSPartA_STDEditor
             this.comboBox_Elem1.Items.Add("first_elem");
             this.comboBox_Elem1.Items.Add("second_elem");
             this.comboBox_Elem1.Items.Add("third_elem");
-            this.comboBox_Elem1.Items.Add("forth_elem");
+            this.comboBox_Elem1.Items.Add("fourth_elem");
             this.comboBox_Elem1.Items.Add("fifth_elem");
             this.comboBox_Elem1.Items.Add("sixth_elem");
             this.comboBox_Elem1.Items.Add("seventh_elem");