Fix :group for customisation

purcell · purcell · commit 4c8cbd0d7fce · 2016-06-04T10:18:34.000+12:00
It's not good practice to create new top-level customisation groups: 'environment is the best fit here.
diff --git a/indent-guide.el b/indent-guide.el
@@ -80,7 +80,7 @@
 
 (defgroup indent-guide nil
   "Show vertical lines to guide indentation."
-  :group 'emacs)
+  :group 'environment)
 
 (defcustom indent-guide-char "|"
   "Character used as vertical line."
