Add SPC o which-key prefix name: user bindings

CHANGELOG.develop

@@ -735,6 +735,7 @@ Other:
   - Added evil key bindings for visualizer and window mode of =undo-tree=
     (thanks to Rich Alesi)
   - Improved =which-key= replacement regular expressions (thanks to duianto)
+  - Added ~SPC o~ which-key prefix name: =user bindings= (thanks to duianto)
 - Improvements:
   - Rewrote window layout functions for ~SPC w 1~, ~SPC w 2~, ~SPC w 3~, and
     ~SPC w 4~ (thanks to Codruț Constantin Gușoi):

layers/+spacemacs/spacemacs-defaults/keybindings.el

@@ -50,6 +50,7 @@
                                        ("m"   "major mode commands")
                                        ("n"   "narrow/numbers")
                                        ("N"   "navigation")
+                                       ("o"   "user bindings")
                                        ("p"   "projects")
                                        ("q"   "quit")
                                        ("r"   "registers/rings/resume")