[TD] detail view: add missing tooltip

src/Mod/TechDraw/Gui/TaskDetail.ui

@@ -213,7 +213,7 @@
      <item row="4" column="0">
       <widget class="QLabel" name="label_8">
        <property name="text">
-        <string>Scale</string>
+        <string>Scale Factor</string>
        </property>
       </widget>
      </item>
@@ -259,6 +259,12 @@
      </item>
      <item row="3" column="2">
       <widget class="QComboBox" name="cbScaleType">
+       <property name="toolTip">
+        <string>Page: scale factor of page is used
+Automatic: if the detail view is larger than the page,
+                   it will be scaled down to fit into the page
+Custom: custom scale factor is used</string>
+       </property>
        <item>
         <property name="text">
          <string>Page</string>