Major change to [[link]] widget.

module/ssg/widgets/link.scm

 (define-module (ssg widgets link)
   :use-module (ice-9 regex)
+  :use-module (srfi srfi-88)
   :use-module (ssg config)
   :use-module ((ssg lib) :select (url-append))
   :export (link-to full-link-to doc widget))
@@ -31,5 +32,10 @@ Which might produce
                   (assoc-ref (config) 'host)
                   (link-to item))))
 
-(define* (widget to)
-  (delay (link-to to)))
+(define* (widget key: to text)
+  "link
+
+Emits the absolute URL of another page within the site."
+  (delay
+    `(a (@ (href ,(link-to to)))
+        ,text)))