Template:Television episodes set in decade category/doc

Creates a category of the form "Television episodes set in the YYY0s", where YYY0s is a 4-digit decade.

e.g.
 * Category:Television episodes set in the 1970s ✅
 * Category:Television episodes set in the 2020s ✅

It is not for use on other categories, e.g.
 * Category:Television episodes set in 1990 ❌

Errors
If the template is used on an invalid page, an error message is generated and the page is categorised in:
 * Category: (population: )

Errors include:


 * The page is not in the category namespace
 * The page's title does not take the form "Television episodes set in YYY0s"