fuse: print help text in generator

pkg/arvo/gen/hood/fuse.hoon

@@ -8,5 +8,8 @@
 ::::
   ::
 :-  %say
-|=  [[now=@da eny=@uvJ bec=beak] [des=desk bas=beak con=(list [beak germ]) ~] ~]
-[%kiln-fuse des bas con]
+|=  [[now=@da eny=@uvJ bec=beak] [arg=[?(~ [des=desk bas=beak con=(list [beak germ]) ~])]] ~]
+:-  %kiln-fuse
+?~  arg
+  ((slog (turn `wain`help-text |=(=@t leaf+(trip t)))) ~)
+[des bas con]:arg

pkg/arvo/lib/hood/kiln.hoon

@@ -56,6 +56,7 @@
       gim=?(%auto germ)                                 ::
   ==
 +$  kiln-fuse
+  $@  ~
   $:  syd=desk
       bas=beak
       con=(list [beak germ])
@@ -388,6 +389,7 @@
 ::
 ++  poke-fuse
   |=  k=kiln-fuse
+  ?~  k  abet
   abet:(emit [%pass /kiln/fuse/[syd.k] %arvo %c [%fuse syd.k bas.k con.k]])
 ::
 ++  poke-cancel