org-agenda: Fix search view's display of command keys

* lisp/org-agenda.el (org-search-view): Specify the keymap for the
substitute-command-keys call because, as of b6c5a174d, this call is
made outside of the agenda buffer.

lisp/org-agenda.el

@@ -4610,7 +4610,7 @@ is active."
 	  (add-text-properties pos (1- (point)) (list 'face 'org-warning))
 	  (setq pos (point))
 	  (unless org-agenda-multi
-	    (insert (substitute-command-keys "\
+	    (insert (substitute-command-keys "\\<org-agenda-mode-map>\
 Press `\\[org-agenda-manipulate-query-add]', \
 `\\[org-agenda-manipulate-query-subtract]' to add/sub word, \
 `\\[org-agenda-manipulate-query-add-re]', \