Enhance C-c C-c in agenda buffers

* lisp/org-agenda.el (org-agenda-ctrl-c-ctrl-c): Don't try to
deactivate columns as `org-columns-toggle-or-columns-quit' is
already bound to `C-c C-c' when the column view is active.

* lisp/org.el (org-ctrl-c-ctrl-c): Update docstring.

lisp/org-agenda.el

@@ -10546,9 +10546,9 @@ when defining today."
     (org-agenda-todo arg)))
 
 (defun org-agenda-ctrl-c-ctrl-c ()
-  "If columns are active, deactivate them."
+  "Set tags in agenda buffer."
   (interactive)
-  (when org-agenda-columns-active (org-columns-quit)))
+  (org-agenda-set-tags))
 
 (provide 'org-agenda)
 

lisp/org.el

@@ -17810,7 +17810,7 @@ Otherwise, return a user error."
 
 This command does many different things, depending on context:
 
-- If column view is active, quit it.
+- If column view is active, in agenda or org buffers, quit it.
 
 - If there are highlights, remove them.
 
@@ -17819,9 +17819,10 @@ This command does many different things, depending on context:
 
 - If the cursor is on a statistics cookie, update it.
 
-- If the cursor is in a headline, prompt for tags and insert them
-  into the current line, aligned to `org-tags-column'.  When called
-  with prefix arg, realign all tags in the current buffer.
+- If the cursor is in a headline, in an agenda or an org buffer,
+  prompt for tags and insert them into the current line, aligned
+  to `org-tags-column'.  When called with prefix arg, realign all
+  tags in the current buffer.
 
 - If the cursor is in one of the special #+KEYWORD lines, this
   triggers scanning the buffer for these lines and updating the