Add newline

Author: RyanLua

docs/source/usage.rst

@@ -72,4 +72,4 @@ Reference
         * ``{owner_username}`` - The owner's username: ``raenlua``
         * ``{post_caption}`` - The post's caption: ``This is a post caption.``
         * ``{post_shortcode}`` - The post's shortcode: ``C8wRGmyR-6N``
-        * ``{post_image_url}`` - The post's image URL: ``https://www.instagram.com/p/C8wRGmyR-6N/media``
+        * ``{post_image_url}`` - The post's image URL: ``https://www.instagram.com/p/C8wRGmyR-6N/media``