Instruction added for use in template files

Author: tevko

readme.md

@@ -1,9 +1,25 @@
 This plugin tells WordPress to create three additional sizes for images you upload. Then it outputs special HTML (via a shortcode) that works with the Picturefill library to achieve responsive images in content.
 
 ### Usage
-
+	
+	Shortcode - 
     [responsive imageid="12" size1="0" size2="500" size3="1000"]
 
+    PHP (use in template files) -
+
+    <span data-picture>
+		<?php 
+			$image = 'the id of your image';
+			$mappings = array(
+	            0 => 'small-img', 
+	            250 => 'large-img',
+	            1000 => 'full-width'
+	        );
+		?>
+	   	<?php echo getPictureSrcs($image, $mappings) ?>
+	   	<noscript> <?php echo wp_get_attachment_image($image, $mappings[2]) ?> </noscript>
+	</span>
+
 ### Prereqs
 
 Make sure your current theme has