Use
<includeonly>{{Template doc page transcluded}}</includeonly>- or
<includeonly>{{Template doc page transcluded|pagename}}</includeonly>
Place at the top of a template documentation page (usually a "Template:Template name/doc" page) that is transcluded on the template's own page (Template:Template name). If the documentation page is not named "doc" and/or its transclusion is via another subpage (e.g. "Template:Template name/example"), use the second form of syntax above and replace pagename accordingly (i. e. with "example"; it is always supposed that the documentation is on a subpage of the template page.
- Note: All four add tagged pages properly to Category:Template documentation