Use defcustom and change README wording.

Use defcustom for string-inflection-skip-backward-when-done instead of
defvar and create a custom group.  Improve the wording in some parts
of the README.

Author: LaurenceWarne

README.org

@@ -13,7 +13,7 @@
 #+BEGIN_SRC elisp
 (require 'string-inflection)
 
-;; C-q C-u is the key bindings similar to Vz Editor.
+;; C-q C-u is similar to the keybinding used by Vz Editor.
 (global-unset-key (kbd "C-q"))
 (global-set-key (kbd "C-q C-u") 'my-string-inflection-cycle-auto)
 
@@ -60,9 +60,9 @@
 
 #+END_SRC
 
-** How to use
+** How to Use
 
-We will change as follows each type =C-q C-u= Place the cursor in the =emacs_lisp=.
+For each of the following, place the cursor at =emacs_lisp= and type =C-q C-u=, the results will be as follows:
 
 In the case of =string-inflection-ruby-style-cycle=
 
@@ -84,7 +84,7 @@ The =string-inflection-all-cycle=, conversion often. However,
 conversion occurs even when there is no need to lower-camelcase.
 Therefore so difficult to use, is not recommended
 
-** Function that can be used alone
+** Standalone Functions
 
 #+BEGIN_SRC elisp
 (string-inflection-underscore-function "EmacsLisp")           ; => "emacs_lisp"

string-inflection.el

@@ -23,15 +23,15 @@
 
 ;;; Commentary:
 
-;; Main functions are three
+;; There are three main functions:
 ;;
 ;;   1. For Ruby -> string-inflection-ruby-style-cycle  (foo_bar => FOO_BAR => FooBar => foo_bar)
 ;;   2. For Python -> string-inflection-python-style-cycle  (foo_bar => FOO_BAR => FooBar => foo_bar)
 ;;   3. For Java -> string-inflection-java-style-cycle  (fooBar  => FOO_BAR => FooBar => fooBar)
 ;;   4. For All  -> string-inflection-all-cycle         (foo_bar => FOO_BAR => FooBar => fooBar => foo-bar => Foo_Bar => foo_bar)
 ;;
 ;;
-;; Setting Example 1
+;; Example 1:
 ;;
 ;;   (require 'string-inflection)
 ;;   (global-unset-key (kbd "C-q"))
@@ -56,7 +56,7 @@
 ;;       (string-inflection-ruby-style-cycle))))
 ;;
 ;;
-;; Setting Example 2
+;; Example 2:
 ;;
 ;;   (require 'string-inflection)
 ;;
@@ -78,16 +78,24 @@
 ;;             '(lambda ()
 ;;                (local-set-key (kbd "C-c C-u") 'string-inflection-java-style-cycle)))
 ;;
-;; You may also consider setting `string-inflection-skip-backward-when-done' to
-;; `t' if you don't like `string-inflect' moving your point to the end of the
-;; word
+;; You can also set `string-inflection-skip-backward-when-done' to `t' if
+;; you don't like `string-inflect' moving your point to the end of the word.
 
 ;;; Code:
 
-(defconst string-inflection-word-chars "a-zA-Z0-9_-")
+(defgroup string-inflection nil
+  "Change the casing of words."
+  :group 'convenience)
+
+(defcustom string-inflection-skip-backward-when-done nil
+  "Controls the position of the cursor after an inflection.
 
-(defvar string-inflection-skip-backward-when-done nil
-  "Whether point just move backward to the beginning of the word after inflecting.")
+If nil remain at the end of the string after inflecting, else move backward to
+the beginning."
+  :group 'string-inflection
+  :type 'boolean)
+
+(defconst string-inflection-word-chars "a-zA-Z0-9_-")
 
 ;; --------------------------------------------------------------------------------