org.texi (Column width and alignment): Fix typo

* org.texi (Column width and alignment): Fix typo.

Thanks to Erich Neuwirth for spotting this.

doc/org.texi

@@ -2318,7 +2318,7 @@ on a per-file basis with:
 
 If you would like to overrule the automatic alignment of number-rich columns
 to the right and of string-rich column to the left, you can use @samp{<r>},
-@samp{c}@footnote{Centering does not work inside Emacs, but it does have an
+@samp{<c>}@footnote{Centering does not work inside Emacs, but it does have an
 effect when exporting to HTML.} or @samp{<l>} in a similar fashion.  You may
 also combine alignment and field width like this: @samp{<l10>}.