org-capture.el: Fix docstring

* lisp/org-capture.el (org-capture-templates-contexts): Fix docstring.

lisp/org-capture.el

@@ -541,8 +541,8 @@ not-in-buffer: command not displayed in matching buffers
 If you define several checks, the agenda command will be
 accessible if there is at least one valid check.
 
-You can also bind a key to another agenda custom command
-depending on contextual rules.
+You can also bind a key to another capture template depending on
+contextual rules.
 
     \\='((\"c\" \"d\" ((in-mode . \"message-mode\"))))