fix typo in learn
@ -18,6 +18,6 @@ utop
# See also:
# OCaml language cheat sheets at /ocaml/
# list of pages: /ocaml/:list
# learn perl: /ocaml/:learn
# learn ocaml: /ocaml/:learn
# ocaml one-liners: /ocaml/1line
# search in pages: /ocaml/~keyword