To add a template to this category, use the following code at the end of the template:
<noinclude>
[[Category:Wikipedia namespace templates|{{PAGENAME}}]]
</noinclude>
If you add this code at the end of the template, please make sure that the opening <noinclude> starts on the same line as the last char of the template code. Experience confirmed by experiments revealed that some templates became seriously defunct when that rule was violated.