improve readme, remove comments about dependencies

modules/lang/sh/README.org

@@ -13,6 +13,8 @@ This module adds support for shell scripting languages.
 
 * Install
 ** Dependencies
-This module has one soft dependency:
+This module has several soft dependencies:
 
 + ~shellcheck~ Enables shell script linting.
++ ~bashdb~ Enables debugging for bash scripts.
++ ~zshdb~ Enables debugging for zsh scripts.

modules/lang/sh/packages.el

@@ -1,9 +1,6 @@
 ;; -*- no-byte-compile: t; -*-
 ;;; lang/sh/packages.el
 
-;; requires shellcheck
-;; optional: zshdb bashdb
-
 (when (featurep! :completion company)
   (package! company-shell))