Support command-not-found on Arch Linux

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
Add Ocaml module

Manage local Ocaml modules with OPAM.

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
Add and update module descriptions
Merge branch 'master' of github.com:sorin-ionescu/prezto into topic.customizations