[Hosts][Settings] Update name and icon of "Additional lines" feature (#21812)

* changes

* restore original icon

* Update description text

src/modules/Hosts/Hosts/Strings/en-us/Resources.resw

@@ -133,10 +133,10 @@
     <value>New entry</value>
   </data>
   <data name="AdditionalLinesBtn.[using:Microsoft.UI.Xaml.Automation]AutomationProperties.Name" xml:space="preserve">
-    <value>Additional lines</value>
+    <value>Additional content</value>
   </data>
   <data name="AdditionalLinesBtn.[using:Microsoft.UI.Xaml.Controls]ToolTipService.ToolTip" xml:space="preserve">
-    <value>Additional lines</value>
+    <value>Additional content</value>
   </data>
   <data name="AdditionalLinesDialog.CloseButtonText" xml:space="preserve">
     <value>Cancel</value>
@@ -145,7 +145,7 @@
     <value>Save</value>
   </data>
   <data name="AdditionalLinesDialog.Title" xml:space="preserve">
-    <value>Additional lines</value>
+    <value>Additional content</value>
   </data>
   <data name="AddNewEntryDialog_Title" xml:space="preserve">
     <value>Add new entry</value>

src/settings-ui/Settings.UI/Strings/en-us/Resources.resw

@@ -2652,7 +2652,7 @@ Activate by holding the key for the character you want to add an accent to, then
     <comment>"Host File Editor" is a product name</comment>
   </data>
   <data name="Hosts_AdditionalLinesPosition.Header" xml:space="preserve">
-    <value>Additional lines position</value>
+    <value>Position of additional content</value>
   </data>
   <data name="Hosts_AdditionalLinesPosition_Bottom.Content" xml:space="preserve">
     <value>Bottom</value>
@@ -2702,4 +2702,7 @@ Activate by holding the key for the character you want to add an accent to, then
   <data name="GPO_IsSettingForced.Title" xml:space="preserve">
     <value>The systems administrator is forcing this setting.</value>
   </data>
+  <data name="Hosts_AdditionalLinesPosition.Description" xml:space="preserve">
+    <value>Additional content includes the file header and lines that can't parse.</value>
+  </data>
 </root>