Improve documentation for capture templates

* doc/org.texi (Template expansion):
* lisp/org-capture.el (org-capture-templates): Clarify documentation.

Suggested-by: Stig Brautaset <stig@brautaset.org>
<http://permalink.gmane.org/gmane.emacs.orgmode/109844>

doc/org.texi

@@ -7306,7 +7306,7 @@ dynamic insertion of content.  The templates are expanded in the order given her
             @r{You may specify a default value and a completion table with}
             @r{%^@{prompt|default|completion2|completion3...@}.}
             @r{The arrow keys access a prompt-specific history.}
-%\\n        @r{Insert the text entered at the nth %^@{@var{prompt}@}, where @code{n} is}
+%\1 %@dots{} %\N @r{Insert the text entered at the Nth %^@{@var{prompt}@}, where @code{N} is}
             @r{a number, starting from 1.}
 %?          @r{After completing the template, position cursor here.}
 @end smallexample

lisp/org-capture.el

@@ -269,7 +269,7 @@ be replaced with content and expanded:
               A default value and a completion table ca be specified like this:
               %^{prompt|default|completion2|completion3|...}.
   %?          After completing the template, position cursor here.
-  %\\N         Insert the text entered at the nth %^{prompt}, where N
+  %\\1 ... %\\N Insert the text entered at the nth %^{prompt}, where N
               is a number, starting from 1.
 
 Apart from these general escapes, you can access information specific to