Define policy for tagging package-template

[weaverba137]

package-template has not been tagged since June 2019. As an affiliated package maintainer, I would love to be able to:

• Target a particular, recent tag of package-template, so that I can say, "this package is compatible with version XYZ of package-template."
• In addition, for each tag of package-template, there should be a clear statement that "this version of package-template is compatible with these versions of Astropy (e.g. Astropy 4.0 - 4.2)."
• This will allow package maintainers to easily construct package dependency trees, among other things.

See also #60.

[weaverba137]

Since package-template is deprecated, this question is moot. Closing.