don't hardcode directory name

dunlin.fnl

@@ -1,4 +1,5 @@
 (local lgi (require :lgi))
+(local lfs (require :lfs))
 (local { : Gtk : Gdk : WebKit2 : cairo } lgi)
 
 (local frame (require :frame))
@@ -7,6 +8,6 @@
 (let [f (frame.new)
       b (buffer.new "main")]
   (f:show-buffer b)
-  (b:visit "file:///home/dan/src/dunlin/doc/index.html"))
+  (b:visit (.. "file://" (lfs.currentdir) "/doc/index.html")))
 
 (Gtk.main)