core-dotspacemacs.el: Fix default value of dotspacemacs-startup-buffe…

…r-show-icons

This is the documented default value in .spacemacs.template, so users
who simply haven't updated their .spacemacs yet to include this
variable at all should get the nil value rather than t.

core/core-dotspacemacs.el

@@ -220,13 +220,13 @@ will be applied to scale the banner."
   'spacemacs-dotspacemacs-init)
 
 (spacemacs|defc dotspacemacs-startup-buffer-show-version t
-  "If true, show Spacemacs and Emacs version at the top right of the
+  "If non-nil, show Spacemacs and Emacs version at the top right of the
 Spacemacs buffer."
   'boolean
   'spacemacs-dotspacemacs-init)
 
-(spacemacs|defc dotspacemacs-startup-buffer-show-icons t
-  "If true, show file icons for entries and headings on spacemacs buffer.
+(spacemacs|defc dotspacemacs-startup-buffer-show-icons nil
+  "If non-nil, show file icons for entries and headings on spacemacs buffer.
 This has no effect in terminal or if \"all-the-icons\" is not installed."
   'boolean
   'spacemacs-dotspacemacs-init)
@@ -242,7 +242,7 @@ This has no effect in terminal or if \"all-the-icons\" is not installed."
   'spacemacs-dotspacemacs-init)
 
 (spacemacs|defc dotspacemacs-check-for-update nil
-  "If non nil then spacemacs will check for updates at startup
+  "If non-nil then spacemacs will check for updates at startup
 when the current branch is not `develop'. Note that checking for
 new versions works via git commands, thus it calls GitHub services
 whenever you start Emacs."