My wiki users are confused about adding TemplateData. We use the Wikipedia `{{documentation}}` template. My users often add `<templatedata>` to both the template itself and the `/doc` subpage, without meaning to, because the "Manage TemplateData" button appears on both. I know you display a warning about it on the template page, but I have another suggested solution.
Please allow a wiki to officially designate a particular subpage for template documentation. For example:
```
//LocalSettings.php:
$wgTemplateDataSubpage = "doc";
```
If this variable is set, then the "Manage TemplateData" button would appear //only// when editing the `/doc` subpage, not when editing the template itself. This prevents users from writing redundant `<templatedata>` blocks on the template + the subpage.
I suspect you can dream up other interesting applications, if the wiki has a known standard subpage for docs.