README.md in usps_flags-0.3.15 vs README.md in usps_flags-0.3.16

@@ -132,13 +132,16 @@
 
 - You can explicitly set `svg_file` to `""` to suppress printing the SVG content
   to console/log.
 - Calling `.png` requires `png_file` to be set.
 
-## Burgees Extension
+## Extensions
 
 There is an extension to this gem for handling squadron burgees:
 [USPSFlags::Burgees](https://github.com/jfiander/usps-flags_burgees)
+
+There is an extension to this gem for handling grade insignia:
+[USPSFlags::Grades](https://github.com/jfiander/usps-flags_grades)
 
 ## Security
 
 This gem is cryptographically signed. To be sure the gem code hasn’t been
 tampered with: