This documentation is transcluded from Template:Documentation/doc. (edit | history)
This template automatically displays a documentation box like you are seeing now, of which the content is transcluded from another page. It is intended for pages which are transcluded in other pages, i.e. templates, whether in the template namespace or not.
Usage
<noinclude>{{Documentation}}</noinclude>
Best practice
This code should be added at the bottom of the template code, with no extra space before "<noinclude>" (which would cause extra space on pages where the template is used). The parameter can be used as shown above to transclude an arbitrary documentation page.
Categories and interwiki links that apply to the template itself should be added to the documentation page, inside <includeonly> </includeonly> tags. For more complex cases, see Wikipedia:Template documentation#Categories and interwiki links.
If the documentation page contains includeonly or noinclude tags as part of the documentation, replace the "<" with "<".
Rationale
Use of this template allows templates to be protected where necessary, while allowing anyone to edit the documentation, categories, and interwiki links.