Add webp to expires rules for Nginx

roles/webserver/templates/nginx/vhost_expires.j2

@@ -19,7 +19,7 @@ location ~* \.(?:rss|atom)$ {
 }
 
 # Media: images, icons, video, audio, HTC
-location ~* \.(?:jpg|jpeg|gif|png|ico|gz|svg|svgz|mp4|ogg|ogv|webm|htc)$ {
+location ~* \.(?:jpg|jpeg|webp|gif|png|ico|gz|svg|svgz|mp4|ogg|ogv|webm|htc)$ {
     expires 1M;
     access_log off;
     add_header Cache-Control "public";