Add whitespace package to spacemacs layer

Diminish lighter to Ⓦ

doc/DOCUMENTATION.md

@@ -806,8 +806,8 @@ eⓅ           | [e-project][e-project] mode
 (Ⓟ)          | paredit mode
 Ⓢ            | flyspell mode
 (Ⓢ)          | [smartparens][sp] mode
+Ⓦ            | whitespace mode
 Ⓨ            | [yasnippet][yasnippet] mode
-(Ⓐ)           | [anaconda-mode][anaconda-mode]
 
 **Note:** in terminal the regular indicators are used instead of the utf-8
 ones.

spacemacs/packages.el

@@ -96,6 +96,7 @@
     visual-regexp-steroids
     volatile-highlights
     wdired
+    whitespace
     window-numbering
     yasnippet
     zenburn-theme
@@ -1870,6 +1871,11 @@ determine the state to enable when escaping from the insert state.")
                                        :action message))
       (evil-leader/set-key "RET" 'wand:execute))))
 
+(defun spacemacs/init-whitespace ()
+  (use-package whitespace
+    :defer t
+    :config (spacemacs|diminish whitespace-mode " Ⓦ")))
+
 (defun spacemacs/init-yasnippet ()
   (use-package yasnippet
     :commands yas-global-mode