Make Y equivalent to y$.

This is much more consistent with C and D and is even recommended by vim
itself.

doc/DOCUMENTATION.org

@@ -694,6 +694,9 @@ Additional information may as well be displayed in the minibuffer.
   opposite direction in =Vim=, but in =Spacemacs= it is the major mode specific
   leader key by default (which can be set on another key binding in the
   dotfile).
+- The ~Y~ key does not yank the whole line. It yanks from the current point to
+  the end of the line. This is more consistent with the behavior of ~C~ and ~D~
+  and is also recommended by the vim documentation.
 
 Send a PR to add the differences you found in this section.
 

spacemacs/packages.el

@@ -717,6 +717,13 @@
       (define-key evil-window-map (kbd "<right>") 'evil-window-right)
       (define-key evil-window-map (kbd "<up>") 'evil-window-up)
       (define-key evil-window-map (kbd "<down>") 'evil-window-down)
+      ;; Make Y equivalent to y$
+      (defun spacemacs/evil-yank-to-end-of-line ()
+        "Yank from point to end of line."
+        (interactive)
+        (evil-yank (point) (point-at-eol)))
+      (define-key evil-normal-state-map (kbd "Y") 'spacemacs/evil-yank-to-end-of-line)
+      (define-key evil-motion-state-map (kbd "Y") 'spacemacs/evil-yank-to-end-of-line)
 
       (evil-leader/set-key "re" 'evil-show-registers)