Rephrase images_featured_explanation (commons-app#6484)

Make the text of the panel consistent with its title.
The title is "Featured images", so the text should
use the same term.

Also move this resource next to the title, to make it easier
for the translators.

Author: amire80

app/src/main/res/values/strings.xml

@@ -133,6 +133,7 @@
   <string name="title_activity_settings">Settings</string>
   <string name="title_activity_signup">Sign Up</string>
   <string name="title_activity_featured_images">Featured Images</string>
+  <string name="images_featured_explanation">Featured images are contributions by highly skilled photographers and illustrators that the Wikimedia Commons community has chosen as some of the highest quality on the site.</string>
   <string name="title_activity_custom_selector">Custom Selector</string>
   <string name="title_activity_category_details">Category</string>
   <string name="title_activity_review">Peer Review</string>
@@ -529,7 +530,6 @@ Upload your first media by tapping on the add button.</string>
   <string name="error_occurred_in_picking_images">Error occurred while picking images</string>
 
   <string name="please_wait">Please wait…</string>
-  <string name="images_featured_explanation">Featured pictures are images from highly skilled photographers and illustrators that the Wikimedia Commons community has chosen as some of the highest quality on the site.</string>
   <string name="images_via_nearby_explanation">Images Uploaded via Nearby places are the images which are uploaded by discovering places on the map.</string>
   <string name="thanks_received_explanation">This feature allows editors to send a Thank you notification to users who make useful edits – by using a small thank link on the history page or diff page.</string>
   <string name="copy_image_caption_description">Copy to the next items</string>